docs: point to full list of supported clipboard tools

[maxbrunet]

I spotted that in the latest release

xclip is for X11, wl-clipboard is for Wayland, and there actually are others:

                                                              clipboard-tool
The presence of a working clipboard tool implicitly enables the '+' and '*'
registers. Nvim looks for these clipboard tools, in order of priority:

  - g:clipboard
  - pbcopy, pbpaste (macOS)
  - wl-copy, wl-paste (if $WAYLAND_DISPLAY is set)
  - xclip (if $DISPLAY is set)
  - xsel (if $DISPLAY is set)
  - lemonade (for SSH) https://github.com/pocke/lemonade
  - doitclient (for SSH) http://www.chiark.greenend.org.uk/~sgtatham/doit/
  - win32yank (Windows)
  - termux (via termux-clipboard-set, termux-clipboard-set)
  - tmux (if $TMUX is set)

https://neovim.io/doc/user/provider.html#clipboard-tool

Windows does not seem to come with a pre-installed one either.

And as always, thank you for AstroNvim! ❤️

[github-actions]

Use the following updater settings in your user/init.lua file, restart, and run :AstroUpdate to test this pull request:

  updater = {
    channel = "nightly",
    branch = "docs/clipboard-tool",
    remote = "maxbrunet",
    remotes = {
      ["maxbrunet"] = "maxbrunet/AstroNvim",
    },
  },

[maxbrunet]

You might want to use paths to disable the above message when there is no config change
https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore

[mehalter]

@maxbrunet thanks for this contribution! It will make the documentation a lot more precise and accurate :D

[mehalter]

LGTM