docs(completion): instructions for zsh 1password completions

Description

A documentation note for those who are using zsh and the 1Password glab plugin.

Since 1Password sets up an alias glab='op plugin run -- glab' completions will not work unless setopt completealiases is run.

Also noticed a typo in one of the other commands.

Relevant thread: https://gitlab.slack.com/archives/C0380FL4K1R/p1670567850345299

How has this been tested?

Tested locally by having 1password glab plugin installed. Completions only work if setopt completealiases is run.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)