Document 'tt cfg' (#3722)

Author: andreyaksenov

doc/reference/tooling/tt_cli/cfg.rst

@@ -0,0 +1,35 @@
+Environment configuration
+=========================
+
+..  code-block:: bash
+
+    tt cfg COMMAND [command flags]
+
+``tt cfg`` manages a ``tt`` environment :ref:`configuration <tt-config_file>`.
+
+
+Commands
+--------
+
+..  container:: table
+
+    ..  list-table::
+        :widths: 20 80
+        :header-rows: 0
+
+        *   -   ``dump``
+            -   Print a ``tt`` environment configuration.
+
+                Flags:
+
+                *   ``-r``, ``--raw``: Print a raw content of the ``tt.yaml`` configuration file.
+
+
+Examples
+--------
+
+The following command prints a ``tt`` environment configuration:
+
+..  code-block:: bash
+
+    tt cfg dump

doc/reference/tooling/tt_cli/commands.rst

@@ -16,6 +16,8 @@ help for the given command.
             -   Build an application locally
         *   -   :doc:`cat <cat>`
             -   Print the contents of ``.snap`` or ``.xlog`` files into stdout
+        *   -   :doc:`cfg <cfg>`
+            -   Manage a ``tt`` environment configuration
         *   -   :doc:`check <check>`
             -   Check an application file for syntax errors
         *   -   :doc:`clean <clean>`
@@ -64,6 +66,7 @@ help for the given command.
 
     build <build>
     cat <cat>
+    cfg <cfg>
     check <check>
     clean <clean>
     completion <completion>