Updated documentation

Author: Dryvnt

README.md

@@ -21,6 +21,7 @@ It is more convenient to map `:ClangFormat` to your favorite key mapping in norm
 If you install [vim-operator-user](https://github.com/kana/vim-operator-user) in advance, you can also map `<Plug>(operator-clang-format)` to your favorite key bind.
 
 `:ClangFormatAutoToggle` command toggles the auto formatting on buffer write.
+`:ClangFormatAutoEnable` command enables the auto formatting on buffer write. Useful for automatically enabling the auto format through a vimrc. `:ClangFormatAutoDisable` turns it off.
 
 ### What is the difference from `clang-format.py`?
 
@@ -111,6 +112,11 @@ autocmd FileType c,cpp,objc map <buffer><Leader>x <Plug>(operator-clang-format)
 nmap <Leader>C :ClangFormatAutoToggle<CR>
 ```
 
+```vim
+" Enable auto formatting on c files:
+au FileType c ClangFormatAutoEnable
+```
+
 ### For More Information
 
 ```