Documentation formatting adjustments

Author: BrandonMathis

README.md

@@ -76,6 +76,7 @@ uploading SSH keys to GitHub):
     cd swift
     ./utils/update-checkout --clone-with-ssh
 
+#### CMake
 [CMake](http://cmake.org) is the core infrastructure used to configure builds of
 Swift and its companion projects; at least version 2.8.12.2 is required. Your
 favorite Linux distribution likely already has a CMake package you can install.
@@ -85,23 +86,32 @@ command line tools to your `PATH`:
 
     export PATH=/Applications/CMake.app/Contents/bin:$PATH
 
+#### Ninja
 [Ninja](https://ninja-build.org) is the current recommended build system
 for building Swift and is the default configuration generated by CMake. If
 you're on OS X or don't install it as part of your Linux distribution, clone
 it next to the other projects and it will be bootstrapped automatically:
 
-    git clone https://github.com/ninja-build/ninja.git
+##### Build from source
+**Via https**
 
-or
+    git clone https://github.com/ninja-build/ninja.git && cd ninja
+    git checkout release
+    cat README
 
-    git clone git@github.com:ninja-build/ninja.git
+**Via ssh**
 
-You can also install CMake and Ninja on OS X using a third-party
-packaging tool like [Homebrew](http://brew.sh)…
+    git clone git@github.com:ninja-build/ninja.git && cd ninja
+    git checkout release
+    cat README
+
+#### Install via third-party packaging tool (OSX only)
+
+**[Homebrew](http://brew.sh/)**
 
     brew install cmake ninja
 
-…or [MacPorts](https://macports.org).
+**[MacPorts](https://macports.org)**
 
     sudo port install cmake ninja