Fix grammar-o.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194283 91177308-0d34-0410-b5e6-96231b3b80d8

docs/ClangTools.rst

@@ -88,8 +88,8 @@ Clang-format is both a :doc:`library <LibFormat>` and a :doc:`stand-alone tool
 <ClangFormat>` with the goal of automatically reformatting C++ sources files
 according to configurable style guides.  To do so, clang-format uses Clang's
 ``Lexer`` to transform an input file into a token stream and then changes all
-the whitespace around those tokens.  The goal is for clang-format to both serve
-both as a user tool (ideally with powerful IDE integrations) and part of other
+the whitespace around those tokens.  The goal is for clang-format to serve both
+as a user tool (ideally with powerful IDE integrations) and as part of other
 refactoring tools, e.g. to do a reformatting of all the lines changed during a
 renaming.