RFR: 2101: Change confusing requirement text

[Zhao Song]

On Wed, 8 Nov 2023 17:36:17 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> The checkbox list in "Progress" in the PRs body says:
> 
> "Commit message must refer to an issue"
> 
> but it is not really talking about the commit message, but the PR title. The "refer to an issue" is also vague; especially since the only time you will be hit by this problem is when you are a newcomer, and do not understand what is expected of you.
> 
> The text should be rephrased to be more helpful to newcomers.

Looks good to me, but it's better to get approval from Erik.

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Marked as reviewed by zsong (Reviewer).

PR Review: https://git.openjdk.org/skara/pull/1584#pullrequestreview-1721404011