Add note of putting labels to the RELEASE PR (#5574)

* Add note of containing RELEASE PR

Signed-off-by: Tetsuya KIKUCHI <97105818+t-kikuc@users.noreply.github.com>

* clarify

Signed-off-by: Tetsuya KIKUCHI <97105818+t-kikuc@users.noreply.github.com>

---------

Signed-off-by: Tetsuya KIKUCHI <97105818+t-kikuc@users.noreply.github.com>

Author: t-kikuc

RELEASES.md

@@ -78,6 +78,8 @@ This may also contain some minor features, but ensure that it does NOT contain a
 - Get a review and merge.
 
 ### Backport fixes and Release Note
+
+- Put labels of `cherry-pick` and `vX.Y.Z` to the PR of updating the `RELEASE` file to prevent conflicts.
 - Run `cherry_pick` workflow
   - Label the merged PR you want to cherry pick with `cherry-pick` , `vX.Y.Z`
     (e.g. v0.48.6 https://github.com/pipe-cd/pipecd/pulls?q=is%3Apr+label%3Acherry-pick+is%3Aclosed+label%3Av0.48.6)