add changes document

changes.md

+## Version 1.4.0
+
+### Features
+
+  * `sort=true` to sort items within sections alphabetically
+  * `@set` tag in module comments; e.g, can say `@set sort=true`
+  * `@classmod` tag for defining modules that export one class
+  * can generate Markdown output
+  * Can prettify C as well as Lua code with built-in prettifier
+  * lfs and lpeg references understood
+  * 'pale' template available
+  * multiple return groups
+  * experimental `@error` tag
+  * Moonscript and plain C support
+
+
+### Fixes
+
+  * works with non-compatibily Lua 5.2, including `markdown.lua`
+  * module names can not be types
+  * all `builtin` Lua files are requirable without `module`
+  * backticks expand in copyright and other 'info' tabs
+  * `-m` tries harder to resolve methods
+  * auto-scroll in navigation area to avoid breaking identifiers
+  * better error message for non-luadoc-compatible behaviour
+  * custom see references fixed
+
+
+