Fix various issues with Markdown docs

docs/ccache_mac.md

 # Using CCache on Mac
 
 [ccache](http://ccache.samba.org/) is a compiler cache. It speeds up
 recompilation of C/C++ code by caching previous compilations and detecting when
 the same compilation is being done again. This often results in a significant
 speedup in common compilations, especially when switching between branches. This
 page is about using ccache on Mac with clang and the NinjaBuild system.
 
 [TOC]
 
 ## Installation
 
 In order to use [ccache](http://ccache.samba.org) with
-[clang](http://code.google.com/p/chromium/wiki/Clang), you need to use the
+[clang](clang.md), you need to use the
 current [git HEAD](http://ccache.samba.org/repo.html), since the most recent
 version (3.1.9) doesn't contain the
 [patch needed](https://github.com/jrosdahl/ccache/pull/4) for using
 [the chromium style plugin](clang.md#Using_plugins).
 
 To install ccache with [homebrew](http://mxcl.github.com/homebrew/), use the
 following command:
 
 ```shell
 brew install --HEAD ccache
@@ skipping 65 matching lines @@
 ninja -C out/Release chrome
 ```
 
 ## Optional Steps
 
 *   Configure ccache to use a different cache size with `ccache -M <max size>`.
     You can see a list of configuration options by calling ccache alone.  * The
     default ccache directory is `~/.ccache`. You might want to symlink it to
     another directory (for example, when using FileVault for your home
     directory).