gx already does what go does

At least, I think it does. check out :h gx.

Thanks for asking. In a lot of cases this is true - go works the same way as go. However, there a also distinguishing features like positioning patterns (https://github.com/jceb/vim-textobj-uri#add-positioning-patterns). In addition, this plugin turns URIs into text objects that can be copied, deleted aso.

I guess it would be good to explain these differences in the documentation.