docs: changelog update for upcoming 2.19.4 release

changelog.asc

@@ -53,6 +53,14 @@ In 2020, implementing Anki's latest scheduling improvements would have taken yea
 * https://crowdin.com/project/ankidroid[New community-provided language translations]
 * https://github.com/ankidroid/Anki-Android/milestone/64?closed=1[Full changelog]
 
+== Version 2.19.4 (20250110)
+* Restore the 2.19 series to the Play Store for Android versions 6 and older
+  We do our best to make sure old devices are not forced into obsolescence
+  We had to drop support for Android < 6 in AnkiDroid 2.20, but we intended
+  to make sure 2.19 was still available and instead the Play Store removed it
+* As ever, huge thanks for the https://opencollective.com/ankidroid[donations] 😍
+  they help us maintain support for old devices much longer than other apps,
+  and keep old versions available for them even when we are forced to move on
 
 == Version 2.19.3 (20241129)
 * Huge batch of fixes for 2.19 series - see main 2.19.1 notes below 👇