Add an image description for visually impaired users

[moggers87]

Coming across one of these toots/tweets might be a bit confusing as the toot/tweet only contains a wiki page title and link.

Something like "Teenage Mutant Ninja Turtles logo but the text has been replaced with " would be enough IMO. Mastodon.py has support for this via media_post, but I'm not sure about tweepy.

[catleeball]

This is a great idea, thank you! If I get a spare minute to edit the bot a bit, I'll look into adding image descriptions hopefully in the next iteration.