Record the vendor naming cleanup in the changelog

CHANGELOG.md

@@ -90,6 +90,16 @@ ADR-007 and ADR-002.
 
 ### Fixed
 
+- **The shipped catalog offered two ways to spell the same vendor, and one row
+  that should never have left a test.** `HP Inc.` and `Zebra Technologies` were
+  empty rows duplicating `HP` and `Zebra`, which carry every model between
+  them; neither exists in this site's database, so they would have arrived as
+  duplicates at a new site and nowhere else. `UnscopedLiveVendor` was a test
+  artifact: `export_catalog.py` reads the live development database, so a row
+  left behind by a lab run was published as reference data. The canonical name
+  is whichever spelling holds the entries, which is why it is `Dell Inc.` but
+  `HP` and `Zebra`. Vendors 51 to 48.
+
 - **The shipped seed catalog contained duplicate vendors, models and operating
   systems.** Four space-stripped twins, each with a correctly spaced original
   already present, so a new site inherited the same company listed twice.