Document usage instructions for the CLI

Signed-off-by: Akashdeep Dhar <akashdeep.dhar@gmail.com>

Author: gridhead

README.md

@@ -13,29 +13,77 @@ Duffy is the middle layer running ci.centos.org that manages the provisioning, m
 
 ### Installation
 To install Duffy:
-* Clone the repository.
-* Install using Poetry: `poetry install`
+1. Clone the repository and navigate into the project directory.
+   ```
+   git clone https://github.com/CentOS/duffy.git
+   cd duffy
+   ```
+2. Set up and activate a virtual environment.
+   * Using native virtual environment
+     ```
+     python3 -m venv duffyenv
+     source duffyenv/bin/activate
+     ```
+   Or
+   * Using virtualenv wrapper
+     ```
+     virtualenv duffyenv
+     source duffyenv/bin/activate
+     ```
+   Or
+   * Using Poetry virtual environment shell
+     ```
+     poetry shell
+     ```
+3. Install using Poetry
+   ```
+   poetry install
+   ```
 
-### Running Duffy using poetry
+### Running Duffy server
 
-There are two ways to run the app using the virtual environment poetry manages for you:
+#### Viewing CLI usage
 
 ```
-poetry run uvicorn duffy.app.main:app --reload
+duffy --help
 ```
 
-Or:
-
 ```
-poetry shell
-uvicorn duffy.app.main:app --reload
+Usage: duffy [OPTIONS]
+
+  Duffy is the middle layer running ci.centos.org that manages the
+  provisioning, maintenance and teardown / rebuild of the Nodes (physical
+  hardware for now, VMs coming soon) that are used to run the tests in the CI
+  Cluster.
+
+Options:
+  -p, --portnumb INTEGER          Set the port value [0-65536]
+  -6, --ipv6                      Start the server on an IPv6 address
+  -4, --ipv4                      Start the server on an IPv4 address
+  -l, --loglevel [critical|error|warning|info|debug|trace]
+                                  Set the log level
+  --version                       Show the version and exit.
+  --help                          Show this message and exit.
 ```
 
-### Running Duffy in an explicitly defined virtual environment
+#### Starting the server at port 8080 using IP version 4 and setting the log level to `trace`
 
-If you create a virtual environment by yourself, poetry will install into this if it's activated. In
-this environment, simply run the app like this:
+```
+duffy -p 8000 -4 -l trace
+```
 
 ```
-uvicorn duffy.app.main:app --reload
+ * Starting Duffy...
+ * Port number : 8000
+ * IP version  : 4
+ * Log level   : trace
+INFO:     Started server process [104283]
+INFO:     Waiting for application startup.
+TRACE:    ASGI [1] Started scope={'type': 'lifespan', 'asgi': {'version': '3.0', 'spec_version': '2.0'}}
+TRACE:    ASGI [1] Receive {'type': 'lifespan.startup'}
+TRACE:    ASGI [1] Send {'type': 'lifespan.startup.complete'}
+INFO:     Application startup complete.
+INFO:     Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
 ```
+
+Exit out of the server using `Ctrl` + `C`