Updating devcontainer setup and related documentation

.devcontainer/dev.js

@@ -0,0 +1,9 @@
+// Using port 3333 is important when running the client web app separately
+const Path = require('path')
+module.exports.config = {
+  Port: 3333,
+  ConfigPath: Path.resolve('config'),
+  MetadataPath: Path.resolve('metadata'),
+  FFmpegPath: '/usr/bin/ffmpeg',
+  FFProbePath: '/usr/bin/ffprobe'
+}