Add github https command for ninja.

Author: Greg Parker

README.md

@@ -107,6 +107,10 @@ 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/martine/ninja.git
+
+or
+
     git clone [email protected]:martine/ninja.git
 
 You can also install CMake and Ninja on OS X using a third-party