Add link to the repo with 3rd party Lark grammars

docs/index.rst

@@ -79,6 +79,7 @@ Resources
 -  :doc:`philosophy`
 -  :doc:`features`
 -  `Examples`_
+-  `Third-party examples`_
 -  `Online IDE`_
 -  Tutorials
 
@@ -111,6 +112,7 @@ Resources
 
 
 .. _Examples: https://github.com/lark-parser/lark/tree/master/examples
+.. _Third-party examples: https://github.com/ligurio/lark-grammars
 .. _Online IDE: https://lark-parser.github.io/lark/ide/app.html
 .. _How to write a DSL: http://blog.erezsh.com/how-to-write-a-dsl-in-python-with-lark/
 .. _Program Synthesis is Possible: https://www.cs.cornell.edu/~asampson/blog/minisynth.html