See https://github.com/silverstripe/silverstripe-framework/issues/9232.
Also simplifies composer instructions a bit:
- Removes composer update --no-dev references, that's a bit of an edge case that people can just discover on getcomposer.org if they need it
- Changed example from the unused and oudated silverstripe/forum to silverstripe/blog
- Updated example versions to 4.x
- Remove "updating composer" section, it now tells you if its out of date
- Remove ss-auto-git-ignore module reference. The module hasn't been updated in ages, and it's much less necessary now that all relevant modules are on composer
- Add .env example config to getting started docs, I didn't realise it was stripped from the default --prefer-dist composer install
- Stronger wording around "use composer"
- Consistent domain and email address naming
- Removed example for publishing non-composer modules (those shouldn't be encouraged)
- Removed instructions for installing modules from archives
[ci skip]
* Remove module specific subthemes documentation as it's removed
* Added notes about cascading theme configuration
* Update links to Themes listing to point to addons
* Remove references to tarballs, and put composer publishing instructions in place instead
