Improved documentation around adding tabs to UI when mounting resque-web

[Jakanapes]

We are using resque-scheduler-web along with resque-web to get the scheduled and delayed tabs in the resque UI, but that gem hasn't been updated in 7 years. I had to fork it due to URI.encode issues.

Noticed that there is a way add those tabs in this gem, but unclear about how to do so when resque-web is mounted in the routes.

The readme only says to

resque-web ~/yourapp/config/resque_config.rb