Remove outdated part of help message.

The styles are now documented with the -style option. This fixes
llvm.org/PR15689.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179017 91177308-0d34-0410-b5e6-96231b3b80d8

tools/clang-format/ClangFormat.cpp

@@ -139,7 +139,6 @@ int main(int argc, const char **argv) {
   cl::ParseCommandLineOptions(
       argc, argv,
       "A tool to format C/C++/Obj-C code.\n\n"
-      "Currently supports LLVM and Google style guides.\n"
       "If no arguments are specified, it formats the code from standard input\n"
       "and writes the result to the standard output.\n"
       "If <file> is given, it reformats the file. If -i is specified together\n"