Fix default webserver port in documentation

[robinmulder]

Short description

The default webserver port is 8081, not 8001. This is correct in other parts of the documentation but not on the settings page.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[Habbie]

Thanks!