help-docs: Move help center documentation to top level directory.

These files are not Jinja2 templates, so there's no reason that they needed
to be inside `templates/zerver`. Moving them to the top level reflects their
importance and also makes it feel nicer to work on editing the help center content, 
without it being unnecessary buried deep in the codebase.

help/configure-notification-bot.md

@@ -0,0 +1,81 @@
+# Notification bot
+
+The Zulip notification bot automatically generates messages for
+various organization level events, including:
+
+* Stream settings changes such as [name](/help/rename-a-stream),
+  [description](/help/change-the-stream-description),
+  [permission](/help/stream-permissions) and
+  [policy](/help/stream-sending-policy) updates (sent to the
+  "stream events" topic)
+* A topic being [resolved/unresolved](/help/resolve-a-topic)
+* New public stream announcements (private streams are not announced)
+* New user announcements
+
+The notification bot also generates automated private messages to
+individual users for some user specific events, such as [being
+subscribed to a stream][add-users-to-stream] by another user.
+
+Additionally, when [moving messages to another stream][move-messages],
+users can have the notification bot send automated notices to help
+others find the moved content.
+
+Organization administrators can configure where (and whether)
+[new stream](#new-stream-announcements) and
+[new user](#new-user-announcements) announcement messages are sent.
+
+Stream messages sent by the notification bot (including the topic)
+are translated into the language that the organization has configured
+as the [organization language for automated messages and invitation
+emails][org-lang]. Private messages sent by the notification bot to
+a user will use [their preferred language](/help/change-your-language).
+
+## Configure notification bot
+
+{!admin-only.md!}
+
+### New stream announcements
+
+You can configure where the Zulip notification bot
+[announces][new-stream-options] new public streams, or disable the new
+stream announcement messages entirely. The topic for these messages
+is "new streams".
+
+{start_tabs}
+
+{settings_tab|organization-settings}
+
+1. Under **Automated messages and emails**, configure **New stream
+   announcements**.
+
+{!save-changes.md!}
+
+{end_tabs}
+
+### New user announcements
+
+You can configure where the Zulip notification bot announces new users,
+or disable the new user announcement messages entirely. The topic for
+these messages is "signups".
+
+{start_tabs}
+
+{settings_tab|organization-settings}
+
+1. Under **Automated messages and emails**, configure **New user
+   announcements**.
+
+{!save-changes.md!}
+
+{end_tabs}
+
+## Related articles
+
+* [Organization language for automated messages and invitation emails][org-lang]
+* [Streams and topics](/help/streams-and-topics)
+
+[add-users-to-stream]: /help/add-or-remove-users-from-a-stream#add-users-to-a-stream
+[api-create-user]: https://zulip.com/api/create-user
+[new-stream-options]: /help/create-a-stream#stream-options
+[org-lang]: /help/configure-organization-language
+[move-messages]: /help/move-content-to-another-stream