Hosted instance has no terms of service

[rmg]

The README.md describes how to set up a repo to use a shared/public instance of mention-bot hosted at https://mention-bot.herokuapp.com/ which is very cool and highly appreciated.

It would make it even easier for foundation and corporation run OSS projects to use the bot if the instance on Heroku had some sort of terms of service that explicitly granted permission to use it instead of what is only implied by the instructions.

Being able to use the hosted instance instead of deploying their own might also make it easier for people who are afraid of the BSD+PATENTS combo that this repo uses.