[docs] loop pragmas: options implying transformations
[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: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@374756 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang