Add documentation for signalling server

apps/signalling-service/.env.example

@@ -0,0 +1 @@
+PORT=4444

apps/signalling-service/.gitignore

@@ -1 +1,2 @@
-node_modules
+node_modules
+.env

apps/signalling-service/README.md

@@ -0,0 +1,28 @@
+This is a signalling server that is used to establish WebRTC connections between users. It is built using Node.js and Socket.IO.
+
+## Getting Started
+
+First, install the dependencies:
+
+```bash
+npm install -g pnpm
+
+pnpm install --frozen-lockfile
+
+# if pnpm install --frozen-lockfile fails, try running
+pnpm install
+```
+
+Then, follow the `.env.example` file and create a `.env` file in the current directory. Replace the necessary values within.
+
+```bash
+PORT=4444
+```
+
+First, run the development server:
+
+```bash
+pnpm dev
+```
+
+## Build Dockerfile (TODO)

apps/signalling-service/package.json

@@ -4,7 +4,8 @@
   "description": "",
   "main": "server.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "dev": "node server.js"
   },
   "type": "module",
   "keywords": [],