minor style change: function names should be lowercase and module name should match repo name

[martinclauss]

Hey :) Thanks for this nice plugin!

I'd like to suggest to rename the module from better-comment.lua to better-comments.lua so that it better matches the repository name.
Also function names should be snake case (ref: https://github.com/luarocks/lua-style-guide). Maybe you could also change this, so that the setup function can be called as setup() like in most of the other plugins.

Thanks for your time and effort!