Add TCM cluster config

Author: p7nov

doc/reference/tooling/tcm/tcm_cluster_config.rst

@@ -1,4 +1,4 @@
-..  _tcm_connect_clusters:
+..  _tcm_configuring_clusters:
 
 Configuring clusters
 ====================
@@ -7,6 +7,116 @@ Configuring clusters
     :start-after: ee_note_tcm_start
     :end-before: ee_note_tcm_end
 
-|tcm_full_name| features a built-in editor for Tarantool EE cluster configurations.
+|tcm_full_name| features a built-in text editor for Tarantool EE cluster configurations.
+
+When you :ref:`connect a cluster <tcm_connect_cluster>` to |tcm|, it gains access
+to the cluster's centralized configuration storage: an etcd or a Tarantool cluster.
+|tcm| has both read and write access to the cluster configuration. This enables
+the configuration editor to work in two ways:
+
+*   If a configuration already exists, the editor shows its current state.
+*   When you change the configuration in the editor and apply changes, they
+    are sent to the configuration storage.
+
+To learn how to write Tarantool cluster configurations, see :ref:`configuration`.
+
+..  _tcm_configuring_clusters_manage:
+
+Managing a cluster's configuration
+----------------------------------
+
+The configuration editor is available on the **Cluster** > **Configuration** page.
+
+To start managing a cluster's configuration, select this cluster in the **Cluster**
+drop-down and go to the **Configuration** page.
+
+..  _tcm_configuring_clusters_add_file:
+
+Adding a configuration file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A cluster configuration in |tcm| can consist of one or multiple YAML files.
+When there are multiple files, they are all considered parts of a single cluster
+configuration. You can use this for structuring big cluster configurations.
+
+To add a cluster configuration file, click the plus icon (**+**) below the page title.
+
+The empty configuration file appears in the editor window on the right. Now you
+can add content to it.
+
+..  _tcm_configuring_clusters_edit_file:
+
+Editing a configuration file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To edit a cluster configuration file:
+
+#.  Select the cluster in the **Cluster** drop-down and go to the **Configuration** page.
+
+#.  Select the file to edit in the file list on the left.
+    It open in the interactive text editor window on the right.
+
+
+..  _tcm_configuring_clusters_download:
+
+Deleting a configuration file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To delete a cluster configuration file:
+
+#.  Select the cluster in the **Cluster** drop-down and go to the **Configuration** page.
+
+#.  Select the file to delete in the file list on the left.
+
+#.  Click the **Delete** button beside the filename and confirm the deletion.
+    Now the file is deleted from |tcm|, but the actual configuration that the cluster
+    uses remains unchanged
+
+#.  Click **Apply** to send the changes to the configuration storage.
+
+.. warning::
+
+    When you apply changes after deleting a file, the corresponding configuration
+    part is *actually deleted* from the configuration storage. The can break the
+    cluster's functioning once its configuration is reloaded.
+
+..  _tcm_configuring_clusters_save:
+
+Saving a configuration draft
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+you can either save it in |tcm| or
+send to the configuration storage and apply to the cluster.
+
+
+To save a cluster configuration draft after editing, click **Save** in the **Cluster configuration** page.
+
+.. warning::
+
+    All unsaved changes are discarded when you leave the **Cluster configuration** page.
+
+If conf
+
+..  _tcm_configuring_clusters_apply:
+
+Applying a configuration
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+When you finish editing configuration files and the configuration is ready to use,
+apply it to the cluster.
+To apply a cluster configuration, click
+
+..  _tcm_configuring_clusters_download:
+
+Downloading a configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To download a cluster configuration file:
+
+#.  Select the cluster in the **Cluster** drop-down and go to the **Configuration** page.
+
+#.  Select the file to download in the file list on the left.
+
+#.  Click the **Download** button beside the filename.
 
-It is synchronized with the