Introduce a separate page Code for code docs

Get rid of one extra level in the left menu (to show more).
Provide a high-level overview of modules including steps.
Move the `Plugins` page under the new section as well.

docs/classes.rst

@@ -1,8 +1,8 @@
 .. _classes:
 
-===============
-    Classes
-===============
+======================
+    Class Overview
+======================
 
 
 Class Structure
@@ -456,12 +456,3 @@ would do, but it makes it explicit and involves correct type conversion:
     >>> command = script.to_shell_command()
     >>> str(command)
     "/bin/bash -c '\ncd $HOME\nls -al\n'"
-
-
-Essential Classes
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. automodule:: tmt
-    :noindex:
-    :members:
-    :undoc-members:

docs/code.rst

@@ -0,0 +1,23 @@
+
+==================
+    Code
+==================
+
+In order to get a quick start with the ``tmt`` source code you
+might want look through the :ref:`classes` first to learn about
+the overall structure of the code. The :ref:`plugins` can help if
+you are planning to write a new plugin. To find detailed
+information about individual classes, modules and packages inspect
+the documentation generated from sources linked below.
+
+.. toctree::
+    :maxdepth: 2
+
+    Class Overview <classes>
+    Plugin Introduction <plugins>
+    tmt <autodocs/tmt>
+
+.. toctree::
+    :maxdepth: 3
+
+    tmt.steps <autodocs/tmt.steps>

docs/contribute.rst

@@ -395,13 +395,3 @@ __ https://src.fedoraproject.org/rpms/tmt/pull-requests
 __ https://copr.fedorainfracloud.org/coprs/psss/tmt/builds/
 __ https://pypi.org/project/tmt/
 __ https://packit.dev/docs/cli/propose-downstream/
-
-
-Code Documentation
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. toctree::
-    :maxdepth: 1
-
-    Overview of important and interesting classes <classes>
-    Documentation generated from sources <autodocs/tmt>

docs/index.rst

@@ -33,5 +33,5 @@ Table of Contents
     Stories <stories>
     Questions <questions>
     Contribute <contribute>
-    Plugins <plugins>
+    Code <code>
     Releases <releases>

docs/plugins.rst

@@ -1,8 +1,8 @@
 .. _plugins:
 
-===============
-    Plugins
-===============
+===========================
+    Plugin Introduction
+===========================
 
 Let's have a look at plugins. Each of the six steps defined by
 :ref:`/spec/plans` supports multiple methods. These methods are