For discussion: Add page about our commitments

1. I wasn't sure what to call it. "Our commitments"? Or is it fine as is?
2. I think it's fair to say we'll respond to email as soon as we can during working hours? (Just to stress here, I really want us to make sure we do not respond out of working hours as I don't want that to become an expectation).
3. Any other thoughts?
I wonder if we should clarify 'it' here ('We will look at it') as it took me a moment to figure out you're referring to bugs in general rather than security issues. I wonder if we should move security issues into their own section so that we can expand on it later as required (to add a PGP key, for example).