Make it more obvious to the developer when the server needs to be restarted

[danielbachhuber]

While working on #497, I was confused at times on why my changes weren't being applied. As it turns out, any changes to the Node server files (e.g. https://github.com/Automattic/studio/pull/497/files#diff-eb193b2da1aa77c2b5b32588db5da8fbc06580ee0de1e0cec4f30893bec6f604R300-R324) require a server restart.

We include some mention of this, but it's not obvious unless you already know where to look.

We should make it more obvious to the developer when they're making changes to a file that require a server restart (or we should just restart the server automatically).

[wojtekn]

For reference, it currently states:

The app automatically launches with the Chromium developer tools opened by default. Changes to the "renderer" process code will automatically reload the app, changes to the main process code require a manual server restart or typing rs into the same terminal where the server was started.

It would be beneficial to make it more precise indeed, e.g., by providing example file paths or functions/classes.