add it to upstream

[j605]

I see that the README mentions that upstreaming this to universal-ctags. Since 1.0 was released quite recently, this would be a great time to do it :)

I just found out about this repo so thanks for maintaining it.

[masatake]

Could you consider to add copyright notice?
Here is an example:
https://github.com/universal-ctags/ctags/blob/master/optlib/elm.ctags

[masatake]

See universal-ctags/ctags#2654 .