Document the need to expand info in dla-needed.txt when reclaiming a package

discussing in this meeting: http://meetbot.debian.net/debian-lts/2022/debian-lts.2022-09-22-13.58.html

pochu> I wanted to bring up how sometimes we reclaim or update a note of a package by just modifying the date, without adding any useful content. I think we should change that practice, and add extra notes rather than modifying a previous one, or reclaiming a package without adding any info
pochu> sometimes that happens more than once (e.g. a whole month without any real update), if there's progress it should be noted, if there's not, perhaps one should give others a chance to work on that package
buxy> That sounds fair, I was also surprised by seeing reclaims where people just add their name back without adding any extra info.
pochu> also about not doing s/20220915/20220922/ without actually editing the note. I'd rather see an extra note, but maybe that's just me