Expand on changelog

Author: tmcw

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 The largest change to documentation.js so far.
 
+**Dropping streams**
+
 This a major refactor of the documentation.js interface with a focus on
 simplifying the system. Up until this point, documentation.js was built around
 [node.js streams](https://nodejs.org/api/stream.html), which are low-level
@@ -11,6 +13,37 @@ majority of documentation.js's internals are simple and synchronous functions
 for which basic functional composition makes more sense than stream
 semantics.
 
+Documentation 3.0.0 uses simple functional composition for operations like
+parmameter inference, rather than streams.
+
+**Stronger support for ES6, ES7, and Flow**
+
+We've switched to [Babel](https://babeljs.io/) as our source code parser,
+which means that we have much broader support of new JavaScript features,
+including import/export syntax and new features in ES6.
+
+Babel also parses [Flow type annotations](http://flowtype.org/docs/type-annotations.html),
+and new inference code means that we can infer
+
+* Parameter names & types
+* Return types
+
+Without any explicit JSDoc tags. This means that for many simple functions,
+we can generate great documentation with less writing.
+
+**mdast-based Markdown output**
+
+We've switched from templating Markdown output with [Handlebars.js](http://handlebarsjs.com/)
+to generating an [abstract syntax tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree)
+of desired output and stringifying it with [mdast](https://github.com/wooorm/mdast).
+This lets documentation.js output complex Markdown without having to worry
+about escaping and properly formatting certain elements.
+
+**Test coverage 100%**
+
+documentation.js returns to 100% test coverage, so every single line
+of code is covered by our large library of text fixtures and specific tests.
+
 ## 2.0.1
 
 * Fixes `@param` tags that refer to properties of unmentioned objects: these