Document httpapi and cliconf plugins (#49503)

* Create new documentation pages for httpapi and cliconf

* Add new documentation to plugins toctree and Makefile

* Add DOCUMENTATION to cliconf

* Apply suggestions from code review

docs/docsite/rst/plugins/httpapi.rst

@@ -0,0 +1,57 @@
+.. _httpapi_plugins:
+
+Httpapi Plugins
+===============
+
+.. contents::
+   :local:
+   :depth: 2
+
+Httpapi plugins tell Ansible how to interact with a remote device's HTTP-based API and execute tasks on the
+device.
+
+Each plugin represents a particular dialect of API. Some are platform-specific (Arista eAPI, Cisco NXAPI), while
+others might be usable on a variety of platforms (RESTCONF).
+
+.. _enabling_httpapi:
+
+Adding httpapi plugins
+-------------------------
+
+You can extend Ansible to support other APIs by dropping a custom plugin into the ``httpapi_plugins`` directory.
+
+.. _using_httpapi:
+
+Using httpapi plugins
+------------------------
+
+The httpapi plugin to use is determined automatically from the ``ansible_network_os`` variable.
+
+Most httpapi plugins can operate without configuration. Additional options may be defined by each plugin.
+
+Plugins are self-documenting. Each plugin should document its configuration options.
+
+
+.. _httpapi_plugin_list:
+
+Plugin List
+-----------
+
+You can use ``ansible-doc -t httpapi -l`` to see the list of available plugins.
+Use ``ansible-doc -t httpapi <plugin name>`` to see detailed documentation and examples.
+
+
+.. toctree:: :maxdepth: 1
+    :glob:
+
+    httpapi/*
+
+
+.. seealso::
+
+   :ref:`Ansible for Network Automation<network_guide>`
+       An overview of using Ansible to automate networking devices.
+   `User Mailing List <https://groups.google.com/group/ansible-devel>`_
+       Have a question?  Stop by the google group!
+   `irc.freenode.net <http://irc.freenode.net>`_
+       #ansible-network IRC chat channel