[docs] loop pragmas: options implying transformations

Following our discussion on the cfe dev list:
http://lists.llvm.org/pipermail/cfe-dev/2019-August/063054.html,
I have added a paragraph that is explicit about loop pragmas, and
transformation options implying the corresponding transformation.

Differential Revision: https://reviews.llvm.org/D66199

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374756 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed