Support more languages in contributing subcommand

[gaocegege]

https://github.com/gaocegege/maintainer/blob/aa310a8938e6f767fdf10aee0d1e09c547949518/contributing/contributing.go#L117

Now contributing only supports golang. But it is easy to extend.

[gaocegege]

• Java: https://google.github.io/styleguide/javaguide.html
• Javascript: https://github.com/airbnb/javascript
• Typescript: TBD, no formal coding style guide
• Scala: http://docs.scala-lang.org/style/
• C++: https://google.github.io/styleguide/cppguide.html
• Python: https://www.python.org/dev/peps/pep-0008/
• PHP: http://www.php-fig.org/psr/psr-2/
• Ruby: https://github.com/bbatsov/ruby-style-guide
• Swift: https://github.com/raywenderlich/swift-style-guide
• R: https://google.github.io/styleguide/Rguide.xml
• Shell: https://google.github.io/styleguide/shell.xml