Update achievement set revision guidelines

docs/guidelines/content/achievement-set-revisions.md

@@ -101,6 +101,8 @@ If you have new ideas after a plan has passed, start a new addendum revision pla
 
 - If you are adding a **similar** concept to one found in the set, where possible reuse the old concept and update it rather than make a new one. This prevents players from having to unnecessarily re-earn achievements, restricts needless changes to sets, and preserves good quality developer work and concepts.
 
+- If you are adding new achievements in which criteria can be proven by prior unlocks then prepare an Achievement Transfer request in `#cleanup-admin` to be processed once the set goes live. This helps to reduce player frustrations and the number of manual unlock requests coming through. For example: Unlock Achievement X for all users who earned Achievements Y and Z.
+
 - Since revisions vary in the amount of adjusted content, they are treated the same as an achievement set reservation. If three months have passed since your revision plan was approved, you will need to provide an update that details the current progress. Not doing so will invalidate the revision and the plan will need to be approved again with a new vote.
 
 ### No Need for Approval Vote
@@ -240,4 +242,4 @@ Revision voting is currently dev-only. While voting is exclusive to Discord, ple
 - All revision types require you to contact active authors of the set and any developer with an active claim.
 - You may contact them in any manner in which you can be reasonably certain they will see it (DMs preferred)
 - If you believe you may be blocked by the user, send a message to [DevCompliance](https://retroachievements.org/createmessage.php?t=DevCompliance&s=Revision%20Contact%20Request%20-%20[Author%20Name]) asking them to contact the author on your behalf. The 72hr maximum wait time will begin upon sending the message to DevCompliance. When doing so, state the user's name, type of revision, and the brief description of what your revision entails as if you were contacting the author directly.
-- Some authors opt out of requiring contact. Check the [Public Opt-Out Sheet](https://docs.google.com/spreadsheets/d/e/2PACX-1vRRSNI9R-ezC0ma7x2BoU2JiZgMu26iht-sIPc56otfJa2sd_8QQCO-V4JXbfsfSUbrl54wib68-Pjp/pubhtml?gid=1195161231&single=true). If the author is listed as opting out of the revision type, they do not need to be contacted. To update your own Opt-Out information, use [this form](https://forms.gle/mgzv7RHbJEPCrxc77).
+- Some authors opt out of requiring contact. Check the [Public Opt-Out Sheet](https://docs.google.com/spreadsheets/d/e/2PACX-1vRRSNI9R-ezC0ma7x2BoU2JiZgMu26iht-sIPc56otfJa2sd_8QQCO-V4JXbfsfSUbrl54wib68-Pjp/pubhtml?gid=1195161231&single=true). If the author is listed as opting out of the revision type, they do not need to be contacted. To update your own Opt-Out information, use [this form](https://forms.gle/mgzv7RHbJEPCrxc77).