You're welcome and thanks for your advice along the way :-)

I went for a chronologic order in CONTRIBUTORS, not for the alphabetic order.
And: Yes, I signed the see Details > Required Signatures ;-)

Extending CONTRIBUTORS file

Thanks for the advice :-) With this Arcanist, they were indeed needed.

Hello :-) Does this mean that self-hosted instance, which do not rate-limit requests, can be listed more easily (e.g. without needing to configure _any_ credentials)?

Awesome! While you replied here, I wrote https://sympa.inria.fr/sympa/arc/swh-devel/2018-03/msg00000.html which this task felt necessary to create first :-D