Update default plugins and docs (#2265)

* Update default plugins

* Update plugin docs with missing plugin

* Fixed broken link in docs

* Update Code of Conduct in docs

* Fix mixup that both plugins are moderation-actions

* fix: adapt server tests to use the rich text plugin

* fix: e2e

* fix: sync docs

plugins/talk-plugin-notifications/README.md

@@ -4,6 +4,7 @@ permalink: /plugin/talk-plugin-notifications/
 layout: plugin
 plugin:
     name: talk-plugin-notifications
+    default: true
     provides:
         - Server
         - Client
@@ -28,4 +29,4 @@ line by adjusting the translation, Talk's default behavior is to add a prefix
 before the subject of each email sent. This is always set to the
 [TALK-EMAIL-SUBJECT-PREFIX](/talk/advanced-configuration/#TALK-EMAIL-SUBJECT-PREFIX)
 configuration variable. You should change this parameter if you want to affect
-how the subject is rendered.
+how the subject is rendered.