Add TCM UI overview (#4285)

Resolves #4159

Author: p7nov

doc/reference/tooling/tcm/_images/tcm_ui_acl.png

@@ -36,6 +36,7 @@ to read data. LDAP authorization is supported as well.
 .. toctree::
     :maxdepth: 1
 
+    tcm_ui_overview
     tcm_connect_clusters
     tcm_cluster_config
     tcm_cluster_monitoring

doc/reference/tooling/tcm/_images/tcm_ui_audit_log.png

@@ -79,6 +79,8 @@ on these pages.
     Roles don't include cluster permissions. Access to connected clusters
     is configured for each user individually.
 
+.. _tcm_access_control_roles_default:
+
 Default roles
 ~~~~~~~~~~~~~
 
@@ -95,6 +97,8 @@ Default roles
     basic administrative *read* permissions that are required to log in to |tcm|
     and navigate to a cluster.
 
+.. _tcm_access_control_roles_manage:
+
 Managing roles
 ~~~~~~~~~~~~~~
 
@@ -115,6 +119,8 @@ table row.
 
     You can delete a role only if there are no users with this role.
 
+.. _tcm_access_control_users:
+
 Users
 -----
 
@@ -156,7 +162,7 @@ To edit a  user, click **Edit** in the **Actions** menu of the corresponding tab
 
 To delete a user, click **Delete**  in the **Actions** menu of the corresponding table row.
 
-.. _tcm_access_control_password:
+.. _tcm_access_control_passwords:
 
 Passwords
 ---------
@@ -171,12 +177,16 @@ Users receive their first passwords during their :ref:`account creation <tcm_acc
 All passwords are governed by the :ref:`password policy <tcm_access_control_password_policy>`.
 It can be flexibly configured to follow the security requirements of your organization.
 
+.. _tcm_access_control_password_change:
+
 Changing your password
 ~~~~~~~~~~~~~~~~~~~~~~
 
 To change your own password, click your name in the top-right corner and go to
 **Settings** > **Change password**.
 
+.. _tcm_access_control_password_users_change:
+
 Changing users' passwords
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -204,6 +214,8 @@ menu of the corresponding **Secrets** table row.
 
     Password expiration can't be reverted.
 
+.. _tcm_access_control_password_block:
+
 Blocking passwords
 ~~~~~~~~~~~~~~~~~~
 

doc/reference/tooling/tcm/_images/tcm_ui_audit_settings.png

@@ -22,6 +22,15 @@ once per second. To pause the visualization, click the button on the left from
 the metrics selector. To stop the visualization, clear the metric selection.
 
 
+..  _tcm_cluster_metrics_instance:
+
+Viewing instance metrics
+------------------------
+
+To view metrics of a specific instance, find this instance on the **Stateboard**,
+click its name, and go to the **Metrics** tab of the instance page.
+
+
 ..  _tcm_cluster_metrics_prometheus:
 
 Monitoring metrics with Prometheus