Correct the links and names in index.md.

docs/index.md

 
 - [Features](#features)
 - [History](#history)
-- [Adding a Language](add_language.html)
-  - [Pronunciation Dictionary](dictionary.html)
-- [Voice Files](voices.html)
-  - [MBROLA Voices](mbrola.html)
-  - [Phonemes](phonemes.html)
-  - [Phoneme Tables](phontab.html)
-- [Intonation](intonation.html)
-- [Markup Tags](ssml.html)
+- [Adding a Language](add_language.md)
+  - [Pronunciation Dictionary](dictionary.md)
+- [Voice Files](voices.md)
+  - [MBROLA Voices](mbrola.md)
+  - [Phonemes](phonemes.md)
+  - [Phoneme Tables](phontab.md)
+- [Intonation](intonation.md)
+- [Markup Tags](ssml.md)
 - [License](../COPYING)
 
 ----------
 but is not as natural or smooth as larger synthesizers which are based on human
 speech recordings.
 
-eSpeak is available as:
+eSpeak NG is available as:
 
-*	A command line program (Linux and Windows) to speak text from a file or
-	from stdin.
-*	A shared library version for use by other programs. (On Windows this is
-	a DLL).
-*	A SAPI5 version for Windows, so it can be used with screen-readers and
-	other programs that support the Windows SAPI5 interface.
-*	eSpeak has been ported to other platforms, including Solaris and Mac OSX.
+*  A command line program (Linux and Windows) to speak text from a file or
+   from stdin.
+*  A shared library version for use by other programs. (On Windows this is
+   a DLL).
+*  A SAPI5 version for Windows, so it can be used with screen-readers and
+   other programs that support the Windows SAPI5 interface.
+*  eSpeak NG has been ported to other platforms, including Solaris and Mac
+   OSX.
 
 ## Features
 
-*	Includes different Voices, whose characteristics can be altered.
-*	Can produce speech output as a WAV file.
-*	SSML (Speech Synthesis Markup Language) is supported (not complete),
-	and also HTML.
-*	Compact size.  The program and its data, including many languages,
-	totals about 1.4 Mbytes.
-*	Can be used as a front-end to [MBROLA diphone voices](mbrola.html).
-	eSpeak NG converts text to phonemes with pitch and length information.
-*	Can translate text into phoneme codes, so it could be adapted as a
-	front end for another speech synthesis engine.
-*	Potential for other languages. Several are included in varying stages
-	of progress. Help from native speakers for these or other languages is
-	welcome.
-*	Written in C.
+*  Includes different Voices, whose characteristics can be altered.
+*  Can produce speech output as a WAV file.
+*  SSML (Speech Synthesis Markup Language) is supported (not complete),
+   and also HTML.
+*  Compact size.  The program and its data, including many languages,
+   totals about 1.4 Mbytes.
+*  Can be used as a front-end to [MBROLA diphone voices](mbrola.html).
+   eSpeak NG converts text to phonemes with pitch and length information.
+*  Can translate text into phoneme codes, so it could be adapted as a
+   front end for another speech synthesis engine.
+*  Potential for other languages. Several are included in varying stages
+   of progress. Help from native speakers for these or other languages is
+   welcome.
+*  Written in C.
 
 The eSpeak speech synthesizer supports over 70 languages, however in many cases
 these are initial drafts and need more work to improve them. Assistance from
 In 2010, Reece H. Dunn started maintaining a version of eSpeak on GitHub that
 was designed to make it easier to build eSpeak on POSIX systems, porting the
 build system to autotools in 2012. In late 2015, this project was officially
-forked to a new eSpeak NG project. The new eSpeak NG project is a significant
+forked to a new __eSpeak NG__ project. The new eSpeak NG project is a significant
 departure from the eSpeak project, with the intention of cleaning up the
 existing codebase, adding new features and adding and improving to the
 supported languages.