Added a dev mode with watchers

package.json

@@ -5,12 +5,17 @@
   "type": "module",
   "main": "index.js",
   "scripts": {
+    "dev": "concurrently --kill-others -n Build,Serve -c auto \"npm run watch-build\" \"npm run serve\"",
+    "watch-build": "nodemon --watch notes --watch build.js --watch markdown.js --watch templates -e js,md,html,css build.js",
+    "build": "node build.js",
     "init": "npm install -g firebase-tools && firebase login",
     "serve": "serve .dist"
   },
   "author": "",
   "license": "ISC",
   "devDependencies": {
+    "concurrently": "^8.2.1",
+    "nodemon": "^3.0.1",
     "serve": "^14.2.1"
   },
   "dependencies": {