Use .md extension for links within repository

This way they work from both GitHub and the website.

Author: adamvoss

_config.yml

@@ -29,3 +29,6 @@ collections:
   docs:
     output: true
     permalink: "/:title:output_ext"
+
+gems:
+  - jekyll-relative-links

examples.md

@@ -33,7 +33,7 @@ Walkthroughs
 
 The two examples below are step-by-step guides into building a schema:
 
--   [a simple example](example1.html) which covers a classical product catalog description.
--   [a more advanced example](example2.html), using JSON Schema to describe filesystem entries in a Unix-like /etc/fstab file.
+-   [a simple example](example1.md) which covers a classical product catalog description.
+-   [a more advanced example](example2.md), using JSON Schema to describe filesystem entries in a Unix-like /etc/fstab file.
 
 The [Space Telescope Science Institute](http://www.stsci.edu/) has also published an [guide aimed at schema authors](http://spacetelescope.github.io/understanding-json-schema/).

index.md

@@ -56,10 +56,10 @@ More
 
 Interested? Check out:
 
--   the [specification](documentation.html)
--   some [examples](examples.html)
+-   the [specification](documentation.md)
+-   some [examples](examples.md)
 -   this [excellent guide](http://spacetelescope.github.io/understanding-json-schema/) for schema authors, from the [Space Telescope Science Institute](http://www.stsci.edu/)
--   the growing list of [JSON (Hyper-)Schema software](implementations.html)
+-   the growing list of [JSON (Hyper-)Schema software](implementations.md)
 
 Questions? Feeling helpful? Get involved on: