Update Moderation Policy to account for triagers

[aduh95]

When the policy was set, the triaggers team did not exist. This PR updates it to include triaggers in what the policy refers to as "Collaborators".

In practice, what does that change/clarify is that:

• Posts from triagers are NOT subject to immediate Moderation (see https://github.com/nodejs/admin/blob/main/Moderation-Policy.md#collaborator-posts for the process for moderating Collaborators posts).
• Members of the triagers team may Moderate Posts within the nodejs/node and nodejs/help repo.

[aduh95]

/cc @nodejs/tsc @nodejs/moderation

[avivkeller]

CC @nodejs/issue-triage

[avivkeller]

FWIW Triagers aren't able (permission-wise) to perform the same actions as the moderation team, such as editing issues, minimizing comments, etc.