docs: add the release-notes improvement bullet to Store listing notes

[nelsonduarte]

What

The 1.15.0 changelog carried six user-facing items, but the Microsoft Store release notes listed only five. The missing entry was the release-notes improvement itself, so Store users saw a shorter summary of the release than users on every other channel. This adds that sixth bullet to RELEASE_NOTES in msix/generate_listing_csv.py, in all eight languages.

Why this wording

The bullet deliberately describes the notes themselves rather than the in-app update dialog. MSIX installs never see that dialog: check_for_update() short-circuits and returns None for externally-managed installs, MSIX included, which is enforced by tests/test_updater_msix.py. Describing an update dialog that Store users cannot reach would have been inaccurate for exactly the audience these notes are written for.

Verification

• Only the ReleaseNotes row changes in the generated CSV: 1 row out of 454.
• Bullet parity holds at 6 bullets in each of the 8 languages.
• Localised lengths run 335 to 1030 characters, inside the 1500-character Partner Center limit. The longest is de-de at 1030.
• No version strings touched; APP_VERSION remains 1.15.0.
• Suite: 746 passed, 2 skipped.

The em dash (U+2014) in the notes title is this file's own existing convention and is left as-is. The bullets themselves use none.

Pre-existing debt in this file, not addressed here

Recorded so it is not lost. None of this is introduced by this PR:

• SEARCH_TERMS['pt-pt'] is written in English (PDF editor offline, offline PDF tools, PDF splitter software, paginate PDF documents), and slots 5 and 6 are empty strings. Every other locale is localised and fills all six. Note that only six slots are defined in total, so the "empty slot 7" is really a slot that does not exist in any language; Partner Center allows a seventh that this generator never emits.
• FEATURE1['zh-cn'] contains the typo 10 0% 离线, a stray space inside "100%". Confirmed programmatically: '10 0%' in FEATURE1['zh-cn'] is True and '100%' in ... is False. This is user-visible on the Chinese Store listing.
• No test covers this file at all. A grep of tests/ for generate_listing_csv and listingData returns nothing. The 1500-character limit and cross-language bullet parity are both validated by hand today. A test asserting those two properties would be cheap and would have caught the missing bullet automatically.

🤖 Generated with Claude Code