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/include/import-how-users-will-log-in.md

@@ -0,0 +1,70 @@
+When user accounts are imported, users initially do not have passwords
+configured. There are a few options for how users can log in for the first time.
+
+!!! tip ""
+
+    For security reasons, passwords are never exported.
+
+### Allow users to log in with non-password authentication
+
+When you create your organization, users will immediately be able to log in with
+[authentication methods](/help/configure-authentication-methods) that do not
+require a password. Zulip offers a variety of authentication methods, including
+Google, GitHub, GitLab, Apple, LDAP and [SAML](/help/saml-authentication).
+
+### Send password reset emails to all users
+
+You can send password reset emails to all users in your organization, which
+will allow them to set an initial password.
+
+If you imported your organization into Zulip Cloud, simply e-mail
+[support@zulip.com](mailto:support@zulip.com) to request this.
+
+!!! warn ""
+
+    To avoid confusion, first make sure that the users in your
+    organization are aware that their account has been moved to
+    Zulip, and are expecting to receive a password reset email.
+
+#### Send password reset emails (self-hosted organization)
+
+{start_tabs}
+
+{tab|default-subdomain}
+
+1. To test the process, start by sending yourself a password reset email by
+   using the following command:
+
+     ```
+     ./manage.py send_password_reset_email -u username@example.com
+     ```
+
+1. When ready, send password reset emails to all users by
+   using the following command:
+
+     ```
+     ./manage.py send_password_reset_email -r '' --all-users
+     ```
+
+{tab|custom-subdomain}
+
+1. To test the process, start by sending yourself a password reset email by
+   using the following command:
+
+     ```
+     ./manage.py send_password_reset_email -u username@example.com
+     ```
+
+1. When ready, send password reset emails to all users by
+   using the following command:
+
+     ```
+     ./manage.py send_password_reset_email -r <subdomain> --all-users
+     ```
+
+{end_tabs}
+
+### Manual password resets
+
+Alternatively, users can reset their own passwords by following the instructions
+on your Zulip organization's login page.