Move 24-bit color / truecolor tip out of tmux section

manual/src/tips-and-tricks/24-bit-color-truecolor.md

@@ -3,3 +3,10 @@
 Delta looks best if your terminal application supports 24 bit colors. See <https://github.com/termstandard/colors#readme>. For example, on MacOS, iTerm2 supports 24-bit colors but Terminal.app does not.
 
 If your terminal application does not support 24-bit color, delta will still work, by automatically choosing the closest color from those available. See the `Colors` section of the help output below.
+
+If 24-bit color is supported by your terminal emulator, then it should have set the `COLORTERM` env var to the value `truecolor` (or `24bit`). If necessary, you can explicitly enable true color, either by using `--true-color=always` or by adding the following to your configuration file:
+
+```gitconfig
+[delta]
+    true-color = always
+```

manual/src/tips-and-tricks/using-delta-with-tmux.md

@@ -6,9 +6,6 @@ If you're using tmux, it's worth checking that 24 bit color is working correctly
 set -ga terminal-overrides ",xterm-256color:Tc"
 ```
 
-and you may then need to quit tmux completely for it to take effect. Note that you may need to explicitly enable true color, either by using `--true-color=always` or by adding the following to your configuration file:
+and you may then need to quit tmux completely for it to take effect.
 
-```gitconfig
-[delta]
-    true-color = always
-```
+If colors look wrong, then see the page on [truecolor/24-bit color](./24-bit-color-truecolor.md) to ensure that this is working correctly.