[janicduplessis]

Description

Main gained package changes after the last 1.20.0 notes update (a03db6e), and that commit failed the full Windows suite, so 1.20.0 is still untagged. The tag will go on this PR's merge commit.

Solution

Adds to docs/releases/1.20.0.md:

• New: ca5b501 (feat: show what the device and launch phases wait on #3370), build.activity in stim status (booting, bundling with Metro's percent, waiting-ready).
• Migration notes: 8d2ab2f (fix(cli): pass child-process arguments as argv and refuse unsafe batch-file arguments on Windows #3346), Windows refusal of unsafe .bat/.cmd arguments and the android.deviceProfile pattern.
• Fixes: 09bc84d (fix(cli): check process identity before two kill sites signal a recorded pid or group #3347) with its follow-up 4d28590 (fix(cli): do not read a killed, unreaped Chrome leader as a profile holder #3372), the identity checks before two kill sites; c2e0771 (fix: make the full Windows unit suite pass (ccache note separators, fixture reaper pid reuse) #3369), the Windows ccache note path separators; fcaddb5 (fix(desktop): follow a remote machine update through waits, refusals and other updates #3286), server.update.status reporting the outcome of an update the server started.
• Docs: 14427a8 (docs: tutorial share step with before/after screenshots and a template PR body #3367), tutorial before/after screenshots and the share template.

Test plan

oxfmt --check on the notes; each line checked against its commit's diff and PR body.