I don't know of such a section, there is simply a section on Referer[sic] request-headers , at large. HTTP -> HTTP and HTTPS -> HTTPS are implied, if the only stated consideration is HTTPS -> HTTP referrals. HTTPS -> HTTPS Referer works on Google Search, which is usually of the most concern.
I see your point, but Mozilla is in an impossible position.
Encrypting people's search is a good idea. Mozilla should do this, and as others in this thread have pointed out, they could be chastised for not having done it.
The fault is Google's who tamper with the referrer data intentionally to obscure the keyword data. They do this for the users 'privacy', but then you can still get the data if you're a paying Adwords customer. I have trouble reconciling 'privacy' and 'you can buy it'.