Grammar and spelling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202318 91177308-0d34-0410-b5e6-96231b3b80d8
Add an explanatory comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202321 91177308-0d34-0410-b5e6-96231b3b80d8
Formatting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202323 91177308-0d34-0410-b5e6-96231b3b80d8