Custom page title

[uboness]

Is your feature request related to a problem? Please describe. Right now the page title is fixed to "Zigbee2MQTT". When you have multiple instance of z2m and you have multiple tab open to these instances, it's hard to distinguish between them (which tab points to which instance).

Describe the solution you'd like The page title should be customizable in the z2m configuration file under the frontend key. E.g.:

frontend: 
  port: 8080
  title: "Z2M - Instance 1"