docs: Copy Block-ABI-Apple.txt to output.

This fixes the URL permanence of that URL. This is a bit of a hack. See
the FIXME in the patch for what the "real" solution should be.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171795 91177308-0d34-0410-b5e6-96231b3b80d8
docs: Fix inconsistent titles.

Sphinx was whining about this.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171796 91177308-0d34-0410-b5e6-96231b3b80d8