Document the Steps for New Deployments to Change the AppName

[casaout]

Notes from SRichner:

package.json, electron-builder-config (productName und appId), im src/electron/electron/main/index.ts no d app user model id uf zile 65, und denn sush überall no womr PersonalAnalytics will ersetze (onboarding, about, etc.)

Consider simplifcations that are possible (e.g. define app name for UI-stuff only once).