docs(CHANGES) align fmt notes with user-facing tone

why: The fmt and formatter-test entries still read like implementation notes; we
want product-level phrasing consistent with the rest of the changelog.

what:
- explain that `vcspull fmt` now merges duplicate workspace sections by default
  and point to `--no-merge` for inspection-only runs
- describe Syrupy snapshot coverage as a guardrail for future fmt changes

Author: tony

CHANGES

@@ -37,10 +37,9 @@ _Upcoming changes will be written here._
 
 #### `vcspull fmt` gains duplicate root merging (#479)
 
-- Detects repeated workspace root labels and merges their repositories during
-  formatting so users keep a single normalized section.
-- Adds `--no-merge` for workflows that need to preserve duplicate entries while
-  still seeing diagnostic warnings.
+- Running `vcspull fmt` now consolidates repeated workspace sections into one
+  merged block so no repositories vanish during cleanup; pass `--no-merge` if
+  you want the command to surface duplicates without rewriting them.
 
 #### `vcspull add` protects workspace configs during imports (#480)
 
@@ -67,8 +66,8 @@ _Upcoming changes will be written here._
 
 #### Snapshot coverage for formatter tests (#479)
 
-- Formatter scenarios now use [Syrupy]-backed JSON and YAML snapshots to guard
-  against regressions in duplicate workspace-root merging.
+- Formatter scenarios are checked against [Syrupy] JSON/YAML snapshots, making it
+  obvious when future changes alter the merged output or log text.
 
 #### CLI `add` path-mode regression tests (#480)