Update CoAP README

Signed-off-by: Drasko DRASKOVIC <drasko.draskovic@gmail.com>

coap/README.md

@@ -1,4 +1,52 @@
-# Mainflux CoAP
+# Mainflux CoAP Adapter
 
-[CoAP (Constrained Application Protocol)](http://coap.technology/) service of Mainflux IoT Cloud.
+Mainflux CoAP adapter provides an [CoAP](http://coap.technology/) API for sending messages through the
+platform.
+
+## Configuration
+
+The service is configured using the environment variables presented in the
+following table. Note that any unset variables will be replaced with their
+default values.
+
+| Variable              | Description       | Default               |
+|-----------------------|-------------------|-----------------------|
+| COAP_ADAPTER_NATS_URL | NATS instance URL | nats://localhost:4222 |
+
+## Deployment
+
+The service is distributed as Docker container. The following snippet provides
+a compose file template that can be used to deploy the service container locally:
+
+```yaml
+version: "2"
+services:
+  adapter:
+    image: mainflux/coap-adapter:[version]
+    container_name: [instance name]
+    ports:
+      - [host machine port]:5683
+    environment:
+      COAP_ADAPTER_NATS_URL: [NATS instance URL]
+```
+
+To start the service outside of the container, execute the following shell script:
+
+```bash
+# download the latest version of the service
+go get github.com/mainflux/mainflux
+
+cd $GOPATH/src/github.com/mainflux/mainflux/cmd/coap
+
+# compile the app; make sure to set the proper GOOS value
+CGO_ENABLED=0 GOOS=[platform identifier] go build -ldflags "-s" -a -installsuffix cgo -o app
+
+# set the environment variables and run the service
+COAP_ADAPTER_NATS_URL=[NATS instance URL] app
+```
+
+## Usage
+
+For more information about service capabilities and its usage, please check out
+the [API documentation](swagger.yaml).