[doc] Fix minor grammatical error in Phabricator.rst

Summary: Test commit, fix minor grammatical error in Phabricator.rst

Reviewers: delcypher

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28214

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291101 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed