doc: write about tt-connect and direct terminals

doc/tooling/tcm/index.rst

@@ -47,4 +47,5 @@ to read data. LDAP authorization is supported as well.
     tcm_dev_mode
     tcm_configuration_reference
     tcm_integrity_check
+    tcm_terminals
     Releases <tcm_releases/index>

doc/tooling/tcm/tcm_terminals.rst

@@ -0,0 +1,22 @@
+..  _tcm_terminals:
+
+Terminals
+=========
+
+|tcm_full_name| (TCM) provides two ways to interact with Tarantool instances:
+
+– ``direct`` — a terminal that connects directly to a Tarantool instance using the go-tarantool <https://github.com/tarantool/go-tarantool/>__ library, bypassing the tt connect utility
+– ``tt-connect`` — a terminal that uses the :ref:`tt-cli` utility to connect to a Tarantool instance
+
+Both terminals allow executing SQL queries, managing cluster state, viewing metrics, and more.
+
+..  _tcm_terminals_direct:
+
+Terminal direct
+---------------
+
+
+..  _tcm_terminals_tt-connect:
+
+Terminal tt-connect
+-------------------

doc/tooling/tcm/tcm_ui_overview.rst

@@ -145,7 +145,9 @@ It provides a set of tabs for performing actions on the selected Tarantool insta
     or as a console output of ``box.cfg``, ``box.info``, and other built-in functions
 -   **SQL** and **Terminal** tabs: run SQL and Lua commands on the instance
 -   **Logs** tab: view instance logs
--   **Slabs** tab: view :ref:`slab allocator <memtx-memory>` statistics
+-   **Slabs** tab: view :ref:`slab allocator <memtx-memory>` statistics. TCM provides two ways to interact with Tarantool instances:
+    – ``direct`` — a terminal that connects directly to a Tarantool instance using the go-tarantool <https://github.com/tarantool/go-tarantool/>__ library, bypassing the tt connect utility
+    – ``tt-connect`` — a terminal that uses the :ref:`tt-cli` utility to connect to a Tarantool instance
 -   **Users** tab: manage Tarantool :ref:`users and roles <tcm_cluster_users>` on the instance
 -   **Funcs**: manage and call stored functions
 -   **Metrics**: view instance metrics