Update the doc content for edpm_network_config

Link: https://issues.redhat.com/browse/OSPRH-4342

docs/source/roles/role-edpm_network_config.rst

@@ -1,10 +1,34 @@
-=============================
+============================
 Role - edpm_network_config
-=============================
+============================
 
-.. note::
-  When the `edpm_network_config_tool` is set to `'os-net-config'`, the `ctlplane_gateway_ip` and `ctlplane_ip`
-  variables must be set on the host.
+Usage
+~~~~~
+
+This Ansible role does the following tasks:
+
+* Read the configured edpm_network_config_tool
+  The following choices can be used to configure the host network:
+  - nmstate, i.e based on systemroles.network
+  - os-net-config, i.e based on custom tasks
+
+* For the latter, prepare to running os-net-config tool in the host
+  It creates necessary folder/files for rendering the network template
+  and the NIC mapping (optional) in the host
+  It also checks for presence of required RPMs
+
+Here is an example playbook to run os-net-config tool:
+
+.. code-block:: YAML
+
+    - name: Apply network_config
+      block:
+        - name: Configure host network with edpm-ansible
+          include_role:
+            name: edpm_network_config
+          vars:
+            edpm_network_config_template: "{{ nic_config_file }}"
+
+.. literalinclude:: ../../../roles/edpm_network_config/tasks/os_net_config.yml
+   :language: YAML
 
-.. include::
-  ../collections/osp/edpm/edpm_network_config_role.rst