doc: update CONTRIBUTING.md

[awklover]

Make sure to read the contributing guidelines before submitting a PR

I have witnessed some of the things happening in this community in recent days. It seems that no one is speaking up for zhouwg.

I think Jeff really did make a mistake:

• He shouldn't dropped some non-tech comments in discussions-14356 although he deleted on July 12 2025.
• Jeff should not be in the thread that has nothing to do with him. I know Jeff is a person with a strong sense of justice. He will express his opinions on things that he thinks are unreasonable even if doing so will bring him trouble. We can all see that the original author of ggml has warned/reminded Jeff not to post any non-technical comments in this tech community on July 12 2025, that's the ostensible direct reason why Jeff was blocked again on July 14 2025.

So the punishment for Jeff is make sense although to be fair it was too severe.

There is an interesting question: why Jeff dropped some non-tech comments in discussions-14356 because I know Jeff is a typical tech-oriented and code-oriented programmer?

Blessed are the pure in heart, for they will see God.
Blessed are the peacemakers, for they will be called children of God.
Blessed are those who are persecuted because of righteousness, for theirs is the kingdom of heaven.
Matthew 5:8-10

This PR attempts to resolve this long-term issue. As the original author of ggml said on July 12 2025:I think we try to accept all points of views . I think this PR may be a good thing for the entire community and prevent Jeff's tragedy from happening again if this PR can be approved, might-be a good thing for Jeff because I don't think Jeff's punishment will be lifted anytime soon.

[awklover]

modify to: Opening a hard-forked PR of other people's original PRs are not allowed unless the opening hard-forked PR with real breakthrough progress can be approved within a week

in other words, hard-fork other's original PRs is allowed, but opening a hard-forked PR should be careful.