release/10.x: no changelog has the Packaging line for the release notes change that shipped in 10.2.0 #538

Problem

10.2.0 changed what a package's release notes are: its version's section of its changelog, in plain text, where they were a link to the latest changelog (#346, PR #348 on this branch). No changelog on release/10.x says so. git grep -i 'release notes' origin/release/10.x -- CHANGELOG.md finds nothing.

#348 carried no changelog line on purpose: the branch was at the released 10.1.0 and no next version was open. The comment on #346 asked whoever opened the next 10.x version to add it. 10.2.0, 10.3.0 and 10.4.0 were opened and released without it.

Found on 2026-11-11 while bringing #347 (the main half) up to date.

Change

On release/10.x, add this line under ### Changed of ## [10.2.0], the version that shipped it, in the root and all four package changelogs:

- Packaging: a package's release notes on nuget.org and in Visual Studio are its version's section of its changelog, in plain text, ending with a link to the changelog at the version's tag, where they were a link to the latest changelog ([Changelog](https://github.com/CaffeinatedCoder/CodoMetis.ValueRanges/blob/main/CHANGELOG.md)).

Check first what the changelog convention tests say about a line added to a released section. The packages of 10.2.0 are immutable, so their release notes on nuget.org stay without the line; only the changelog of record is corrected. Carry the [10.2.0] sections to main with the next carry.

Done when

The five [10.2.0] sections on release/10.x hold the line, and main's copies of those sections follow.