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
* Update the cryptocurrency address with newly created one
* Replace the icon used for the donation address and link
* Replace the word Monero with the word XMR
* Replace the Liberapay placeholder with a link to the documentation
Travis CI is slow, builds are first queued up forever and then the builds
themselves are slow, too.
GitHub Actions run pretty much immediately and are fast. Also separate jobs run
at the same time unlike on Travis CI.
Using sudo with `echo ... | tee /path/to/file` doesn't make sense, as the command requiring the superuser privileges is the `tee` command and not the echo.