arcanist: document aliases

plugins/arcanist/README.md

 ## arcanist
 
-**Maintainer:** [@emzar](https://github.com/emzar)
-
 This plugin adds many useful aliases for [arcanist](https://github.com/phacility/arcanist).
+
+To use it, add `arcanist` to the plugins array of your zshrc file:
+
+```zsh
+plugins=(... arcanist)
+```
+
+## Aliases
+
+| Alias   | Command                            |
+|---------|------------------------------------|
+| ara     | `arc amend`                        |
+| arb     | `arc branch`                       |
+| arco    | `arc cover`                        |
+| arci    | `arc commit`                       |
+| ard     | `arc diff`                         |
+| ardc    | `arc diff --create`                |
+| ardnu   | `arc diff --nounit`                |
+| ardnupc | `arc diff --nounit --plan-changes` |
+| ardpc   | `arc diff --plan-changes`          |
+| are     | `arc export`                       |
+| arh     | `arc help`                         |
+| arl     | `arc land`                         |
+| arli    | `arc lint`                         |
+| arls    | `arc list`                         |
+| arpa    | `arc patch`                        |