fix(foot): drop stale [colors2] section

foot 1.28 rejects the config with "invalid section name: colors2".
The alternate color theme section was renamed to [colors-light]
alongside [colors-dark]; our block only held comments, so it is
removed rather than renamed.

Verified with foot --check-config (exit 0).

defaults/xdg/foot/foot.ini

@@ -140,11 +140,6 @@ search-box-match=cdd6f4 313244
 jump-labels=11111b fab387
 urls=89b4fa
 
-[colors2]
-# Alternative color theme, see man page foot.ini(5)
-# Same builtin defaults as [color], except for:
-# dim-blend-towards=white
-
 [csd]
 # preferred=server
 # size=26