Remove references to capability module in docs and godocs

[damiannolan]

The capability module has been removed as a dependency from IBC in a series of PRs and finally in https://github.com/cosmos/ibc-go/pull/7270.

This issue is a task to follow up on the removal of this module by removing references to it in:

• The ibc-go documentation for the next release (v10)
• Any references to capabilities in godocs across the codebase

[bznein]

I'll assign myself on this one for the second point. I have never touched the docs and I'd rather have someone else do it, someone that know exactly what they are doing :D

[crodriguezvega]

Closed by #7279, #7323, #7293.