dotfiles: update tmux.conf

Now that all my hosts are running new enough userlands to support
the tmux-256color terminfo entry I can use it everywhere. Notably
this enables italics to work inside tmux.

Also update comment about the tmux-specific terminfo extensions
for true color. I need to keep using "Tc" until all my hosts have
tmux 3.2+.

See: https://jdhao.github.io/2018/10/19/tmux_nvim_true_color/
See: https://github.com/tmux/tmux/wiki/FAQ#i-dont-see-italics-or-italics-and-reverse-are-the-wrong-way-round

dotfiles/config/tmux/tmux.conf

@@ -102,14 +102,20 @@ set-option -g status-right '#[fg=colour47]#H #[fg=red]#(cut -d " " -f 1-3 /proc/
 # scrollback buffer
 set-option -g history-limit 4096
 
-# 2020-07-10: According to the tmux FAQ, inside tmux TERM must be "screen",
-# "tmux" or similar (such as "tmux-256color"). Systems with older terminfo
-# like CentOS 7 don't support tmux-256color so let's keep screen-256color
-# for now.
-set-option -g default-terminal "screen-256color"
-# 2022-11-07: Tell Tmux that outside terminal supports true color
+# 2022-11-26: According to the tmux FAQ, inside tmux TERM must be "screen",
+# "tmux" or similar (such as "tmux-256color"). As of CentOS Stream 8, now
+# all my systems support this (check with `infocmp tmux-256color`).
+#
+# See: https://github.com/tmux/tmux/wiki/FAQ#how-do-i-use-a-256-colour-terminal
+set-option -g default-terminal "tmux-256color"
+
+# 2022-11-26: Tell Tmux that the outside terminal supports true color. I
+# need to use the tmux-specific extension "Tc" for now until all my hosts
+# are on tmux 3.2+.
+#
+# See: https://github.com/tmux/tmux/wiki/FAQ#how-do-i-use-rgb-colour
 # See: https://jdhao.github.io/2018/10/19/tmux_nvim_true_color/
-set -ga terminal-overrides ",xterm-256color*:Tc"
+set -as terminal-overrides ",*-256color*:Tc"
 
 #### COLOUR (Solarized dark)