Add zsh/lolcat.zsh rainbow helpers + document in README

README.md

@@ -102,6 +102,45 @@ On top of stock YADR:
 - Misc: `.rainbow_config.json` (rainbowstream), `.nanorc`, `.selected_editor`,
   `.mplayer/config`, `.jigdo-lite`
 
+## Rainbow output (lolcat)
+
+`zsh/lolcat.zsh` wires [lolcat](https://github.com/jaseg/lolcat) (Debian's
+`/usr/games/lolcat`, the truecolor C build) into a few shell helpers. lolcat
+auto-detects a tty — it colorizes straight to the terminal but passes text
+through plain when piped onward, so use `-f`/`--force` to colorize mid-pipeline.
+
+### Opt-in, per command
+
+Prefix any command to rainbow its output:
+
+```sh
+lol fastfetch
+lol git log --oneline
+lol ls -C                 # -C keeps columns: a piped ls otherwise goes single-column
+lolf git diff | less -R   # force color so it survives down a pipeline
+```
+
+### Shortcuts
+
+```sh
+rcat file.txt             # rainbow cat
+rls -la                   # rainbow ls, columns preserved
+some-cmd | rless          # rainbow + pager (less -R)
+```
+
+### Session toggle
+
+Rainbow *all* shell stdout until you turn it off:
+
+```sh
+rainbow_on                # everything is rainbow now
+...
+rainbow_off               # back to normal
+```
+
+Novelty only: it garbles full-screen/interactive programs (vim, less, htop,
+fzf, ssh) and the prompt, and buffers streaming output. Doesn't touch stderr.
+
 ## Upstream
 
 Base is [skwp/dotfiles][yadr] (YADR — Yet Another Dotfiles Repo). All credit