NC13: link to developer manual refers to documentation of NC 12

[cloud2018]

Version NC13.0.0

In the apps-view the last item "i Developer documentation" refers to the documentation of NC 12 instead of NC13. I assume the source is:

server/settings/templates/apps.php

Line 32 in 12c9bad

<a class="app-external icon-info" target="_blank" rel="noreferrer noopener" href="https://docs.nextcloud.org/server/12/developer_manual/"><?php p($l->t('Developer documentation'));?> ↗</a>

[cloud2018]

Also version number 12 in themes\example\defaults.php and CONTRIBUTING.md

themes\example\defaults.php Line 143:
return $this->getDocBaseUrl() . '/server/12/go.php?to=' . $key;

CONTRIBUTING.md Line 61:
[devmanual]: https://docs.nextcloud.org/server/12/developer_manual/
settings\templates\apps.php(32): t('Developer documentation'));?> ?

[MorrisJobke]

Fix is in #8263

[cloud2018]

Are the version numbers in themes\example\defaults.php and CONTRIBUTING.md also fixed?