feature request: --append

[8go]

Is your feature request related to a problem? Please describe.
No problem. Just an idea for an enhancement.

Describe the solution you'd like

• Similar to --edit an --append command that takes the input directly from the commandline.
• Something like: --append=
• Example: cheat --append somecommand "\n\n# example foo\nfoo -bar"
• The result would be that 3 lines ("\n\n# example foo\nfoo -bar") would be
  appended to the end of cheatsheet for somecommand

Additional context

• I wand people to add examples/snippets to the end of cheatsheets via a Matrix bot.
• The Matrix bot users obviously have no access to the remote machine or an editor.
• The simplest implementation for the bot would be to get the contributions from the
  bot users and make a call like cheat --append somecommand $usercontribution
• Yes, I could do an echo $usercontribution >> ~/.config/cheat/cheatsheets/personal/somecommand