github only takes CONTRIBUTING.md as the contributing guidelines

following up "Names and Order of Includes" in google c++ style guide
(https://google.github.io/styleguide/cppguide.html).

with this command: yapf -i --style='{based_on_style: google}' --recursive modules

Correct typos; remove extra period

To separate code reference from description.

The clang-format tool can use the coding style defined in .clang-format
Refer to https://clang.llvm.org/docs/ClangFormatStyleOptions.html for more options