Support Gemini protocol for signatory web sites

[Antolius]

Proposal

Currently the sign form expects URI to signatory's site to use the HTTPS scheme. I propose to broaden this validation rule to include Gemini as well.

Motivation

Gemini specification is designed with reader privacy and simplicity of technical implementation in mind. This results in a community of personal, often self-hosted sites, i.e. decentralization. For example, most Gemini sites run on single tenant servers, and there's no cross-site tracking.

While the goal of Gemini is not to single-handedly replace the big web, it does offer one alternative to the web3 "experience". Along other projects, such as the 512KB Club or indeed the Small Technology Foundation, it is one of the ways of achieving the web0 goal.

While decentralization principle can be applied on the level of individual sites, I believe there's value in applying it also on the level of communities and the technology that enables them. In that respect it would be nice if web0 manifesto site itself supported this technical diversity by accepting Gemini links.