[docs] Add SourceWeb as external example.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176848 91177308-0d34-0410-b5e6-96231b3b80d8

Author: chisophugis

docs/ExternalClangExamples.rst

@@ -28,6 +28,9 @@ that can help developers, generally they must have code available.
 List of projects and tools
 ==========================
 
+`<http://rprichard.github.com/sourceweb/>`_
+   "A C/C++ source code indexer and navigator"
+
 `<https://github.com/etaoins/qconnectlint>`_
    "qconnectlint is a Clang tool for statically verifying the consistency
    of signal and slot connections made with Qt's ``QObject::connect``."