Reword sentence in LangRef
Reword sentence in LangRef

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@309431 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit abecca79fb7339ae17a6d76db141a972fe989855)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm