CHANGELOG: #4884's 3.9.0 entry covers #4939 and #4941

[erikdarlingdata]

What changed

The 3.9.0 entry for the wait-name fix (#4884) is amended to cover #4939 and #4941, which completed it after the release was cut:

• the entry's references gain Lite reads wait history stored with a trailing space as the clean wait name #4939 and Darling reads a wait stored under both spellings as one wait under its clean name #4941, in CHANGELOG.md (the index line) and docs/changelog/3.9.md (the full entry), with their link definitions in order;
• in docs/changelog/3.9.md, two sentences are rewritten. Rows stored with the trailing space before the upgrade now read as the clean name in both apps, so a wait that accrued time under both spellings shows as one row and one series. Lite's wait views also hide the two newly ignored waits in history collected before the upgrade, while Darling, which applies its ignore list as it collects, shows that history until retention removes it;
• tools/changelog/archive-census.txt carries the 3.9.0 archive's new prose hash. The entry count is unchanged (760), and the [3.9.0] Fixed section still lists 511 entries: this amends an entry and adds none.

Checks

tools/changelog/changelog_archive.py verify passes for 3.9.0 (760 index lines for 760 archived entries, and the prose hash matches the census); split, census and roundtrip run clean.

Not changed

No code, configuration or test file.