Escaping a special character in the documentation.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219407 91177308-0d34-0410-b5e6-96231b3b80d8
Implement various matchers around template argument handling.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219408 91177308-0d34-0410-b5e6-96231b3b80d8