Use more streamlined and inclusive pronouns on the distro compatibilty page

[pave-unpaved]

his/her is clunky and sounds bad. their is significantly more streamlined and also has the added benefit of not excluding the probably tiny but still existent group of users/potential users who do not fit into either category.

[paradigm]

The "his/her" thing may be problematically deeply ingrained into my muscle memory. I greped around and am surprised there were no other instances of this on the website. If you see me do the same thing again, note it's probably not a consciously made choice; feel free to politely point it out to me and I'll be happy to change it there as well.