Add spinster.xyz to the list, a newly created TERF instance

[mftrhu]

As per title. It was advertised recently on /r/GenderCritical, and I linked the relevant threads in the spinster_xyz.md file.

[ghost]

Is TERF a serious action or theory, or just a violence against transgender people?

[mftrhu]

If talking about TERFs as a whole, they are a hate group.

If talking about this specific instance - and I'm told that it might get blocked automatically by some as it's a fork of the Gab codebase, which might make this PR unnecessary - they are sourcing their members from known hate subreddits and other TERF spaces.

If talking about my choice to list them under "Violent speech spaces", it's because that heading specifically talks about TERFs:

Violent speech spaces

These instances often advertise themselves as having laissez-faire moderation or as 'not a safe space', what they really mean is that they are a safe space for a variety of violent and/or hateful speech, ideologies and shitty actions, including (but not limited to):

[...]

• TERFs/fake goths