[docs] [NFC] Removed excess spacing

Summary: Removed excess new lines from documentations. As far as I can tell, it seems as though restructured text is agnostic to new lines, the use of new lines was inconsistent and had no effect on how the files were being displayed.

Reviewers: jhenderson, rupprecht, JDevlieghere

Reviewed By: jhenderson

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63971

llvm-svn: 365105