[spec] Using a gitlab

[Stephane Bortzmeyer]

On Sun, Mar 14, 2021 at 05:05:55PM +0000,
 Liam <liam at lmcm.io> wrote 
 a message of 5 lines which said:

> The suggestion of SourceHut sounds like a good compromise if it's
> true that one can participate without an account.

>From their page: "Sourcehut is currently available as a public alpha."
It all depends on whether we want to work on the specification, or if
we want to help test/develop SourceHut.

Installation instructions are quite scary
<https://man.sr.ht/installation.md>.