Drop support for i3

While I first switched to EXWM warily and thinking it would only be temporary,
it seems like this switch is here to stay. It turns out that EXWM was exactly
the integration I've been looking for. How serendipitous it that I found it when
I did.

Thank you, @tazjin.

README.md

@@ -17,7 +17,6 @@ $ cd ..
 $ gclone FabriceCastel/gvcci
 ```
 
-- TODO: Ensure edits to `i3.base` work as expected.
 - TODO: Integrate Emacs themes into wpgtk.
 - TODO: Integrate Vim themes into wpgtk.
 - TODO: add these to the install script
@@ -85,12 +84,6 @@ $ for p in $(cat nix-env.txt); do
 > done
 ```
 
-1. Install i3
-
-```bash
-$ sudo apt-get install i3
-```
-
 1. Install dotfiles
 
 - TODO: include steps 2-4 in the `make install` command.