Since python doesn't have a way to lock deps for a particlar project
by default, I didn't bother with it. This resulted in mkdocs updating at
some point, bringing a breaking change to how tabs are declared and
broken tabs on docs-develop.pleroma.social. I've learned my lesson
and locked deps with pipenv in pleroma/docs!5. This MR updates Pleroma
docs to use the new tab style, fortunately my editor did most of it.
Closes #2045
* It was still written for From Source installs. Now it's both OTP and From Source
* I linked to the cheatsheet where it was about configuration
* I moved the mix tasks of the robot.txt section to the CLI tasks and linked to it
* i checked the code at https://git.pleroma.social/pleroma/pleroma/-/blob/develop/lib/mix/tasks/pleroma/robotstxt.ex and it doesn't seem to more than just this one command with this option
* I also added the location of robot.txt and an example to dissallow everything, but allow the fediverse.network crawlers
* The Thumbnail section still linked to distsn.org which doesn't exist any more. I changed it to a general statemant that it can be used by external applications. (I don't know any that actually use it.)
* Both the logo and TOS need an extra `static` folder. I've seen confusion about that in #pleroma so I added an Important note.
