Add README.md

Author: chetanyakan

README.md

@@ -1,2 +1,43 @@
 # mattermost-plugin-disable-dm
 A mattermost plugin to disable direct messages and group chats.
+
+## Installation and setup
+#### Platform & tools
+- Make sure you have following components installed:
+
+  * Go - v1.11 - https://golang.org/doc/install
+    > **Note:** If you have installed Go to a custom location, make sure the $GOROOT variable is set properly. Refer [Installing to a custom location](https://golang.org/doc/install#install).
+
+  * NodeJS - v10.11 and NPM - v6.4.1 - https://docs.npmjs.com/getting-started/installing-node
+
+  * Make
+
+
+## Building the plugins
+- Run the following commands to prepare a compiled, distributable plugin zip:
+
+```
+$ mkdir -p ${GOPATH}/src/github.com/Brightscout
+$ cd ${GOPATH}/src/github.com/Brightscout
+$ git clone [email protected]:Brightscout/mattermost-plugin-disable-dm.git
+$ cd mattermost-plugin-disable-dm
+$ make dist
+```
+
+
+- This will produce three tar.gz files in `/dist ` directory corresponding to various platforms:
+
+| Flavor  | Distribution |
+|-------- | ------------ |
+| Linux   | `mattermost-plugin-disable-dm-v<X.Y.Z>-linux-amd64.tar.gz`   |
+| MacOS   | `mattermost-plugin-disable-dm-v<X.Y.Z>-darwin-amd64.tar.gz`  |
+| Windows | `mattermost-plugin-disable-dm-v<X.Y.Z>-windows-amd64.tar.gz` |
+
+This will also install, **Glide** - the Go package manager.
+
+## Install the plugin to Mattermost
+- Make sure that the plugin uploads are enabled in `PluginSettings.EnableUploads` in your `config.json` file.
+- Go to **System Console > Plugins (Beta) > Management** and set `Enable Plugins` to `true`.
+- From **System Console > Plugins (Beta) > Management**, upload the plugin generated above based on the OS of your Mattermost server.
+- Once installed, open **System Console > Plugins (Beta) > Team Membership** in left-hand sidebar and configure the plugin settings.
+- Enable the plugin from **System Console > Plugins (Beta) > Management**.