Change git URL to https URL in all docs.

README.md

@@ -22,7 +22,7 @@ for examples and highlights.
 
 To install spack and install your first package:
 
-    $ git clone git@github.com:scalability-llnl/spack.git
+    $ git clone https://github.com/scalability-llnl/spack.git
     $ cd spack/bin
     $ ./spack install libelf
 

lib/spack/docs/getting_started.rst

@@ -9,7 +9,7 @@ Getting spack is easy.  You can clone it from the `github repository
 
 .. code-block:: sh
 
-   $ git clone git@github.com:scalability-llnl/spack.git
+   $ git clone https://github.com/scalability-llnl/spack.git
 
 This will create a directory called ``spack``.  We'll assume that the
 full path to this directory is in some environment called

lib/spack/docs/index.rst

@@ -29,7 +29,7 @@ package:
 
 .. code-block:: sh
 
-   $ git clone git@github.com:scalability-llnl/spack.git
+   $ git clone https://github.com/scalability-llnl/spack.git
    $ cd spack/bin
    $ ./spack install libelf