docs: phone pairing's changelog entry is in v0.3.21

docs/changelog.mdx

@@ -10,6 +10,14 @@ upgrades with `berth upgrade BOX`, or by running the
 again.
 
 ## v0.3.21
+
+- **The phone app pairs from a pasted link.** Its Pair and Boxes screens have
+  *Or paste a pairing link*, for a phone app added to the home screen, which
+  keeps its own storage apart from the browser. A good pairing link no longer
+  says it is damaged, and Back always returns to the list instead of leaving
+  the app. Needs the box upgraded.
+  [Phone](/guides/phone)
+
 - **Turn check: a turn that ends on a question needs you.** Off by
   default; turned on for a box in Settings → Agents, berthd asks a
   decision model you pick about each finished Claude Code or Codex turn:
@@ -162,13 +170,6 @@ again.
   shows the tabs, stays on the one you pick, and no longer jumps from one
   agent's page to the next. Needs the box upgraded.
 
-- **The phone app pairs from a pasted link.** Its Pair and Boxes screens have
-  *Or paste a pairing link*, for a phone app added to the home screen, which
-  keeps its own storage apart from the browser. A good pairing link no longer
-  says it is damaged, and Back always returns to the list instead of leaving
-  the app. Needs the box upgraded.
-  [Phone](/guides/phone)
-
 - **Labs: OpenCode, Gemini CLI and Cursor Agent run structured too.** With
   *Structured agents* on, they start through the Agent Client Protocol: their
   replies stream into the chat, their permission requests come to it (or,