document upgrade procedure (untested) and undo change of prometheus-basic-auth file because it was incorrect

Resolve "NC installation is slow"

Closes #914

See merge request openappstack/openappstack!473

Resolve "Add NC password app"

Closes #906

See merge request openappstack/openappstack!468

Fixes: #914

Resolve "Add NC calendar app"

Closes nextcloud#973 and #905

See merge request openappstack/openappstack!467

TRIGGER_JOBS=enable-nextcloud

Weirdly, going directly from Calendar to Files fails, taiko displays
no files. So we need to take an extra roundtrip via the Dashboard *sigh*

See https://open.greenhost.net/openappstack/openappstack/-/jobs/107990

Closes: #905

Resolve "Loki gets oom killed"

Closes #840 and #911

See merge request openappstack/openappstack!471

Closes: #840

Related: #910