Add documentation for collaboration service (#130)

* Add documentation for bollaboration service

* Fix indent

---------

Co-authored-by: Zenith Yap <[email protected]>

services/collaboration-service/README.md

@@ -0,0 +1,121 @@
+# Collaboration Service
+
+Chat and code editor managed using [socket.io](https://socket.io).
+
+## Architecture
+
+This service uses the matching service which provides a room id. Using socket.io, the two clients joins the same room using the room id. A server will listen for events. When a client emits an event of either message or code-change to the server, the other client will be listening to the server for these events and the front end will be updated.
+
+The high-level architecture of the service can be described with this diagram:
+
+<img src="./docs/diagrams/architecture-diagram.png" width="50%" height="auto">
+<br/><br/>
+
+## Getting started 
+
+Follow the following to run the collaboration service locally.
+
+### Prerequisites
+
+_Preferred setup method is via docker compose._
+
+- Docker Desktop
+
+### Steps
+
+1. Clone the project root repository.
+2. `cd` into the project directory, and then `cd` into `Server-Configs/Without-K8/dev`.
+3. Build the service by running `docker compose up collaboration-service -d`, then wait for the container to start up.
+
+After running the above steps, run `docker logs -f collaboration-service` in terminal. The output should show that the server is running on port 8576.
+<br/><br/>
+
+## API Reference
+
+### Client-emitted events
+
+For clients emitting events to the server, be sure to send a connection message once before sending subsequent messages.
+
+Clients can emit the following Socket.io events to the server:<br/><br/>
+
+Sends a message to the server, which will be received by the other client.
+```websockets
+message
+```
+with the following JSON payload:
+```json
+{
+	"message": string,
+	"roomId": string,
+	"socketId": string,
+	"isMine": boolean
+}
+```
+<br/>
+
+Sends the code to the server, which will be received by the other client.
+```websockets
+code-change
+```
+with the following JSON payload:
+```json
+{
+	"message": string,
+	"roomId": string,
+	"socketId": string,
+	"isMine": boolean
+}
+```
+<br/>
+
+Disconnects the client from the room, which will be received by the other client. 
+```websockets
+disconnect
+```
+<br/>
+
+### Server-emitted events
+
+The server emitted events sends the data sent by a client to the other client in the room.
+
+Clients should listen to the following events emitted from the server:<br/><br/>
+
+Receives the message sent from the other client.
+```websockets
+message
+```
+with the following JSON payload:
+```json
+{
+	"message": string,
+	"roomId": string,
+	"socketId": string,
+	"isMine": boolean
+}
+```
+<br/>
+
+Receives the code sent from the other client.
+```websockets
+code-change
+```
+with the following JSON payload:
+```json
+{
+	"message": string,
+	"roomId": string,
+	"socketId": string,
+	"isMine": boolean
+}
+```
+<br/>
+
+Informs the client that the other client has left the room.
+```websockets
+userDisconnect
+```
+
+## Documentation
+
+- [Socket.io Client API Documentation](https://socket.io/docs/v4/client-api)
+- [Socket.io Server API Documentation](https://socket.io/docs/v4/server-api)