docs: issue #647 create docs/contribution.md and update other documents

README.md

 # eSpeak NG Text-to-Speech
 
 - [Features](#features)
-- [Windows](#windows)
-  - [Binaries](#binaries)
-  - [Building](#building)
-- [Linux, Mac, BSD](#linux-mac-bsd)
-  - [Dependencies](#dependencies)
-  - [Building](#building-1)
-    - [Cross Compilation](#cross-compilation)
-    - [Sanitizer Flag Configuration](#sanitizer-flag-configuration)
-    - [LLVM Fuzzer Support](#llvm-fuzzer-support)
-    - [eSpeak NG Feature Configuration](#espeak-ng-feature-configuration)
-    - [Extended Dictionary Configuration](#extended-dictionary-configuration)
-  - [Testing](#testing)
-  - [Installing](#installing)
-- [Android](#android)
-  - [Dependencies](#dependencies-1)
-  - [Building with Gradle](#building-with-gradle)
-  - [Signing the APK](#signing-the-apk)
-  - [Opening project in Android Studio](#opening-project-in-android-studio)
-  - [Installing](#installing-1)
 - [Documentation](#documentation)
 - [eSpeak Compatibility](#espeak-compatibility)
 - [History](#history)
-- [Feedback](#feedback)
 - [License Information](#license-information)
-
 ----------
 
 The eSpeak NG is a compact open source software text-to-speech synthesizer for 
 
 ## Documentation
 
-1.  [User guide](src/espeak-ng.1.ronn) provides reference and examples for command-line options.
-2.  [Language guide](docs/add_language.md) provides step-by-step instructions, how to add/improve support for language.
-3.  [Index](docs/index.md) provides entries to more detailed information for contributors and developers.
+1. [User guide](src/espeak-ng.1.ronn) provides reference and examples for command-line options.
+2. Look at [contribution guide](docs/contributing.md) to start your contribution.
+3. [Index](docs/index.md) provides full list of more detailed information for contributors and developers.
 
 ## eSpeak Compatibility
 
 existing codebase, adding new features, and adding to and improving the
 supported languages.
 
-
 The *historical* branch contains the available older releases of the original
 eSpeak that are not contained in the subversion repository.
 
 been excluded from the historical commits to align them better with
 the 1.24.02 source commit.
 
-## Feedback
-
-Test latest development version at [eSpeakNG online](https://odo.lv/Espeak).
-
-Report bugs to the [espeak-ng issues](https://github.com/espeak-ng/espeak-ng/issues)
-page on GitHub.
-
-Look at and subscribe to [eSpeakNG mailing list](https://groups.io/g/espeak-ng)
-to view and discuss other related topics.
-
 ## License Information
 
 eSpeak NG Text-to-Speech is released under the [GPL version 3](COPYING) or

docs/contributing.md

+# Contribution Guide
+
+- [Simple steps for your feedback](#simple-steps-for-your-feedback)
+- [Steps for your contribution](#steps-for-your-contribution)
+
+## Simple steps for your feedback
+
+<a class="anchor" id="simplestep1">1. As eSpeak NG is open source software, you can get it working from many different sources, some of which may provide quite
+old version. Before registering new issue, test that issue can be reproduced with latest development version at
+[eSpeak NG online](https://odo.lv/Espeak) site.
+
+<a class="anchor" id="simlestep2">2. Review known [eSpeak NG issues](https://github.com/espeak-ng/espeak-ng/issues), particularly about
+[languages](https://github.com/espeak-ng/espeak-ng/labels/languages%2Fpronunciation) and add your comments 
+on existing issues. If necessary add new issue as described [here](https://help.github.com/en/articles/creating-an-issue).
+
+<a class="anchor" id="simlestep3">3. Look at and subscribe to [eSpeakNG mailing list](https://groups.io/g/espeak-ng)
+to view and discuss other related topics.
+
+## Steps for your contribution
+<a class="anchor" id="step1">1. Get familiar with [additive speech synthesis](https://en.wikipedia.org/wiki/Additive_synthesis).
+
+<a class="anchor" id="step2">2. Create fork of [espeak-ng](https://github.com/espeak-ng/espeak-ng) repository as it is described [here](https://help.github.com/en/articles/fork-a-repo).
+
+<a class="anchor" id="step3">3. [Clone](https://help.github.com/en/articles/cloning-a-repository) and set up your development environment [on your computer](building.md) , or clone it [online](https://odo.lv/EspeakGuide).
+
+<a class="anchor" id="step4">4. Get familiar with [text to phoneme translation](dictionary.md) and how to [add or improve language](add_language.md).
+
+<a class="anchor" id="step5">5. Get familiar with [voice files](voices.md) and [phoneme tables](phontab.md) configuration files.
+
+<a class="anchor" id="step6">6. Make your improvements (i.e. additions or modifications) and check your project with `make check` command. Fix issues if necessary.
+
+<a class="anchor" id="step7">7. If you contribute to an existing language, find language maintainer in language configuration file located in `espeak-ng-data/lang` folder[<sup>1</sup>](#1) and ask him to review your changes. If you can't find language maintainer, you can review list of all contributors[<sup>2</sup>](#2) and contact them. You can also volunteer to become language maintainer just by updating language configuration file.
+
+<a class="anchor" id="step8">8. [Push your changes to GitHub](https://help.github.com/en/articles/pushing-commits-to-a-remote-repository) and create [pull request](https://help.github.com/en/articles/creating-a-pull-request). You can also send changed files by email to [eSpeakNG mailing list](https://groups.io/g/espeak-ng) (but then inlusion of them may take more time).
+
+<a class="anchor" id="step9">9. Wait for feedback of current espeak-ng maintainers[<sup>3</sup>](#3).
+
+<a class="anchor" id="step10">10. If you feel ready to take responsibility, ask existing maintainers to become promoted as a maintainer of the project.
+
+----
+
+<a class="anchor" id="1"></a>1. You can get list of all language maintainers with following commands in your `espeak-ng` folder:
+
+```
+cd espeak-ng-data;grep -ri -A2 -B2 maintainer *
+```
+
+<a class="anchor" id="2"></a>2. You can get list of all contributors with following commands in your `espeak-ng` folder:
+
+```
+git log --pretty="%an %ae%n%cn %ce" | sort|uniq -c|sort -nr
+```
+<a class="anchor" id="3"></a>3. Currently eSpeak NG is maintained only by volunteers in their free time, therefore expected reaction time is one, two weeks.
+

docs/index.md

-# eSpeak NG: Speech Synthesizer
+# eSpeak NG online documentation
 
 - User Guide
   - [espeak-ng Command Line](../src/espeak-ng.1.ronn)
   - [speak-ng Command Line](../src/speak-ng.1.ronn)
   - [Supported Languages](languages.md)
   - [SSML and HTML Support](markup.md)
+- [Contributor Guide](contributing.md)
+  - [Building eSpeak NG](building.md)
 - Creating and Editing Languages and Voices
-  - [Adding or Improving a Language](add_language.md)
+    - [Adding or Improving a Language](add_language.md)
     - [Text to Phoneme Translation](dictionary.md)
     - [Numbers](numbers.md)
   - [Voice Files](voices.md)
   - [Intonation](intonation.md)
 - Phonemes
   - [Phoneme Features and the International Phonetic Alphabet](phonemes.md)
+  - [Phoneme Model](phoneme_model.md)
     - [Kirshenbaum (ASCII-IPA) Transcription Scheme](phonemes/kirshenbaum.md)
     - [X-SAMPA Transcription Scheme](phonemes/xsampa.md)
     - [Conlang X-SAMPA Transcription Scheme](phonemes/cxs.md)
-  - [Phoneme Model](phoneme_model.md)
   - Pronunciation Guides
     - [English](languages/gmw/en.md)
 - [License](../COPYING)