Encourage setting a user agent

[nikkiwd]

Wikimedia's user agent policy says:

If you run a bot, please send a User-Agent header identifying the bot with an identifier that isn't going to be confused with many other bots, and supplying some way of contacting you

and then provides a recommended format to use.

To encourage people to provide a custom user agent, it would help if the documentation would more prominently feature setting a user agent: Rather than only mentioning it as an advanced use case (which it shouldn't be), it could be introduced much earlier on and included in the examples. The example file helloworld.js could set a user agent too.

Perhaps it could also support passing the name, version and contact information via the constructor to make it easier for people to use the suggested format too, e.g.

let bot = new MWBot({ name: "ExampleBot", version: "0.1", contact: "<contact info>" });

which would internally set the user agent string to ExampleBot/0.1 (<contact info>) mwbot/<mwbot version>.