📝 Docs: Suggest filtering out bots

[JoshuaKGoldberg]

We're using this action in github.com/typescript-eslint/typescript-eslint and although it works well, it takes up a lot of workflow space. Since it needs to run on all comments & comment edits, every time another bot such as Netlify updates a comment -which is very often in auto-deploys!- the workflow runs. We filed typescript-eslint/typescript-eslint#8205 on ourselves to disable the action on bots.

Can I suggest having the README.md / first-run docs for accessibility-alt-text-bot disable the workflow for bot accounts?

There's something funny about the default docs of an action authored in the GitHub organization causing many many more workflow GitHub Action runs to take up more of GitHub's $.

[kendallgassner]

Really good point! Thanks for opening this issue. cc. @khiga8