Add description and command line detail to readme

Author: amat27

readme.md

@@ -1,22 +1,49 @@
-# HPC Pack MESOS framework
+# HPC Pack MESOS Framework
 [![Build Status](https://travis-ci.org/amat27/hpcpack-mesos.svg?branch=master)](https://travis-ci.org/amat27/hpcpack-mesos)
 
-A MESOS scheduler framework which accepts offers from MESOS master and builds HPC Pack compute nodes for existing HPC cluster.
+A MESOS scheduler framework, which accepts offers from MESOS master and builds HPC Pack compute nodes for existing HPC cluster.
 
-## Install
-### Dependency
+## Why do I need HPC Pack MESOS Framework
+With the help of HPC Pack MESOS Framework, resource allocation of Microsoft HPC Pack cluster can be managed by existing MESOS cluster, which increases resource utilization.
+
+## What can HPC Pack MESOS Framework do
+HPC Pack Mesos Framework
+- Borrows HPC Pack compute nodes from Mesos cluster, if
+    - HPC Pack has queueing tasks need more resource
+    - Mesos cluster has available resource for HPC Pack
+
+- Returns HPC Pack compute nodes to Mesos cluster, if
+    - The node reached idle time out of Mesos framework
+
+## Installation
+#### Dependency
 * Python 2.7
 * pipenv
 
-### Steps
+#### Installation Steps
 1. Clone this repository
 2. CD to the project folder
-3. `pipenv install`
+3. Run command `pipenv install`
+4. (Optional) You can get Show help info by typing `pipenv run python hpcframework.py -h`
+
+## Command-line usage
+    usage: hpcframework.py [-h] [-g NODE_GROUP] script_path setup_path headnode ssl_thumbprint client_cert
+
+    HPC Pack Mesos framework
+
+    positional arguments:
+    script_path           Path of HPC Pack Mesos slave setup script (e.g. setupscript.ps1)
+    setup_path            Path of HPC Pack setup executable (e.g. setup.exe)
+    headnode              Hostname of HPC Pack cluster head node
+    ssl_thumbprint        Thumbprint of certificate which will be used in installation and communication with HPC Pack cluster
+    client_cert           .pem file of client cert used for HPC Management REST API authentication
 
-### Show help info
-``` pipenv run python hpcframework.py -h```
+    optional arguments:
+    -h, --help            show this help message and exit
+    -g NODE_GROUP, --node_group NODE_GROUP
+                            The node group in which we need to perform grow-shrink.
 
 
 ## FAQ
-### Convert .pfx to .pem using [OpenSSL](https://github.com/openssl/openssl)
+#### Convert .pfx to .pem using [OpenSSL](https://github.com/openssl/openssl)
 ```openssl pkcs12 -in file.pfx -out file.pem -nodes```