Fixes #11959

Co-authored-by: Marc Cornellà <hello@mcornella.com>

Currently the macOS runner is not needed, as we are only checking
zsh syntax. We can reactivate it in the future if needed.

Fixes #10384

Co-authored-by: jxlwqq <jxlwqq@gmail.com>
Co-authored-by: Francesco Ilario <fr.ilario@gmail.com>
Co-authored-by: Marc Cornellà <hello@mcornella.com>

NOTE: this feature is in alpha / preview mode, it is not guaranteed to work 100% of the
time in all cases. If you experience any issues, open an issue or search for an open
one describing your same situation.

To use this, use the zstyle update mode settings [1] with the value `background-alpha`:

  zstyle ':omz:update' mode background-alpha

[1] https://github.com/ohmyzsh/ohmyzsh#getting-updates

* add readme.md for rtx
* add rtx plugin
* update install info
* remove redundant slashes

Closes #11143
Closes #8779
Co-authored-by: Carlo Sala <carlosalag@protonmail.com>

BREAKING CHANGE: `gt` alias clashes with Graphite CLI
(https://graphite.dev). See https://github.com/ohmyzsh/ohmyzsh/pull/11910#issuecomment-1736340910

Co-authored-by: hasecilu <hasecilu@protonmail.com>
Co-authored-by: Rik <gitaarik@posteo.net>
Co-authored-by: Carlo Sala <carlosalag@protonmail.com>

Co-authored-by: Gabriel Akinyosoye <gabrielfemi799@gmail.com>

Co-authored-by: Marcus Müller <marcus_ohmyzsh@baseband.digital>

`vc link` is not needed, as we already have `VERCEL_PROJECT_ID`
defined as an env variable. Currently the `vc link` only creates
a second empty project with the name `installer` as seen in logs:

  Linked to ohmyzsh/installer (created .vercel and added it to .gitignore)
  Vercel CLI 32.2.4

Fixes #11888
Co-authored-by: Matt Cable <github@curiousstranger.org>