Update Prometheus documentation

Closes #27735

See merge request !9060

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Reported in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1905

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Allow creating nested group via UI

See merge request !8786

Nested groups API

See merge request !9034

Fix markdown link in Omniauth docs

See merge request !9082

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Mention reconfigure/restart in omniauth docs

Closes #27901

See merge request !9081

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Add cop that checks if add_column_with_default is used with up/down methods

See merge request !9077

Describe process around cherry-picking during the feature freeze

See merge request !9075

Removed jQuery UI datepicker

See merge request !8421

Removed jQuery UI sortable

See merge request !8478

Fix route rename descendants if route.name is blank

See merge request !9074

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Bypass signup domain validation for external users

Closes #25279

See merge request !8575

Reduce padding of mr widget mini graph

See merge request !9071

Fixes ajax requests when current URL has a trailing slash

Closes #27756

See merge request !9010

Looks for correct key to pass to commit prop. Adds rspec test.

Closes #27880

See merge request !9070

Store group and project full name and full path in routes table

See merge request !8979

Fixed random merge request widget failure

Closes #27806

See merge request !9068