Add note on `--user` option when installing under Drupal 9

See merge request !42

(dev/core#1681) requirements.md - Bump up MySQL requirements

See merge request !43

Note on --user option when installing under Drupal 9 (reference https://github.com/civicrm/cv/issues/113#issuecomment-1071008468)

Remove D8 as a possible requirement since no longer supported

See merge request !41

Fix broken output in dompdf fonts section

See merge request !39

Update ESR Reference in the PHP requirements table and update php...

See merge request !38

Update ESR Reference in the PHP requirements table and update php compatability statements as appropriate

Update WP Multi-Site CiviCRM Multi-Domain Documentation

See merge request !36

Update docs for adding fonts to dompdf now that it's possible to do it and survive upgrade

See merge request !35

Improve instructions about temporary files upload directory

See merge request !34

Add PHP 8.0.

Closes #11

See merge request !33

Fixes #11

Changing link to point to existing documentation for installing l10n /...

See merge request !32

Changing link to point to existing documentation for installing l10n / localisation packages in Update index.md

I left the other part until we actually cut 5.40 due to the framing

Drupal 9 link doesn't exist

See merge request !31

add note about wkhtmltopdf (aka, optional requirements for jumbo shrimp)

See merge request !30

Update index.md

See merge request !29