Major README.md cleaning
Additions:
* Add the invidious logo
* Add Quickstart section
* Add relevant links (instance list, documentation, contribute, donate) directly in the header
Badges:
* Add badges for open issues and PRs
* Add "Awesome Humane Tech" badge, as we're listed there
* Move CI passed/translated badges to the top
* Replace the "license feature" with a proper badge
Major section changes:
* Reword titles
* Rewrite features list
* Promote the screenshots sections. People like screenshots!
* Move "donate" to the end, there is a link at the top anyway
* Move section "made with invidious" after all the other invidious related sections + rename it to "Projects using Invidious"
Other fixes:
* Remove useless HTML in the screenshots table
* Remove extra columns in H2 titles
* Remove all useless lines between sections
* Use markdown for git commands + add the staging step
* Promote invidious redirect in "Extensions"
* Update preference screenshots
