Update GettingStarted guide to recommend that people use the new
official Git repository.

Remove the directions for using git-svn, and demote the prominence of
the svn instructions.

Also, fix a few other issues while I'm in there:

* Mention LLVM_ENABLE_PROJECTS more.
* Getting started doesn't need to mention test-suite, but should
  mention clang and the other projects.
* Remove mentions of "configure", since that's long gone.

I've also adjusted a few other mentions of svn to point to github, but
have not done so comprehensively.

Differential Revision: https://reviews.llvm.org/D56654

llvm-svn: 351130
diff --git a/llvm/docs/index.rst b/llvm/docs/index.rst
index 698e676..4527fe5 100644
--- a/llvm/docs/index.rst
+++ b/llvm/docs/index.rst
@@ -232,7 +232,7 @@
 
 `Documentation for Go bindings <http://godoc.org/llvm.org/llvm/bindings/go/llvm>`_
 
-`ViewVC Repository Browser <http://llvm.org/viewvc/>`_
+`Github Source Repository Browser <http://github.com/llvm/llvm-project//>`_
    ..
 
 :doc:`CompilerWriterInfo`