Refactor our feature parity reference for Cody clients (#579)

This PR ships several improvements to our feature parity reference docs
for Cody clients:

- Removes column for Neovim
- Remove Web from Autocomplete
- Move Commands, Context Selection, Prompts & Prompt Library under Chat
column

- https://sourcegraph.slack.com/archives/C01DXLN3D0T/p1723189248829639

Author: MaedahBatool