help: Add user docs for "Prevent change of name" settings.

templates/zerver/help/change-your-name.md

@@ -8,6 +8,13 @@ you can spell your name exactly how you'd like it to be displayed.
 
 2. Change your name in the **Full name** field.
 
+    !!! warn ""
+        **Note:** Some organization administrators manage users' names
+        via LDAP or another data source, and have disabled the ability
+        for individual users to update their names in Zulip.  If you
+        are unable to edit your name, check with your organization
+        administrators for help.
+
 {!save-changes.md!} account settings.
 
 Congratulations! You have updated your name.

templates/zerver/help/index.md

@@ -127,7 +127,8 @@ as an **organization**.
 * [Allow anyone to join without an invitation](/help/allow-anyone-to-join-without-an-invitation)
 * [Only allow admins to invite new users](/help/only-allow-admins-to-invite-new-users)
 * [Only allow admins to create new streams](/help/only-allow-admins-to-create-new-streams-feature)
-* [Prevent users from changing their email address](/help/disallow-users-to-change-their-email-address)
+* [Prevent users from changing their name](/help/prevent-users-from-changing-their-name)
+* [Prevent users from changing their email address](/help/prevent-users-from-changing-their-email-address)
 * [Restrict editing of old messages and topics](/help/restrict-editing-of-old-messages-and-topics)
 * [Change the default language for your organization](/help/change-the-default-language-for-your-organization)
 * [Add custom emoji](/help/add-custom-emoji)

templates/zerver/help/prevent-users-from-changing-their-name.md

@@ -0,0 +1,14 @@
+# Prevent users from changing their name
+
+{!admin-only.md!}
+
+By default, any user can change their name by going through the
+steps given [here](/help/change-your-name), but administrators can enable a
+setting that prevents them from changing their own names via the Zulip UI.
+
+{!go-to-the.md!} [Organization settings](/#administration/organization-settings)
+{!admin.md!}
+
+2. Select the **Prevent users from changing their name** checkbox.
+
+{!save-changes.md!} organization settings.