Update CHANGELOG.md for 4.9.2 release

[corinagum]

#3302

Changelog

Added

• Resolves #3182. Added stacked suggested actions height properties, by @corinagum, in PR #3235
• Localized strings in Cantonese (yue), by @compulim, in PR #3289

Fixes

• Fixes #3265. Fix styling specificity regression on microphone button, by @corinagum in PR #3276
• Fixes #3279. Fix relative timestamp errored out when showing a time before yesterday, by @compulim in PR #3282
• Fixes #3236, by @compulim in PR #3287
  • Isolated screen reader only live region for incoming activities and added a new <ScreenReaderActivity> component
  • Removed screen reader text for activities outside of live region, including <CarouselFilmstrip>, <StackedLayout>, <TextContent>, and <Timestamp>
  • Updated some accessibility texts
  • Rectified activities render order by delaying activities with replyToId that reference an activity which is not ACK-ed, for up to 5 seconds
  • Disabled widgets will have tabindex="-1" set, instead of disabled attribute
  • Remove tabindex="-1" from Adaptive Cards container
  • Hide activities of type invoke
• Fixes #3294. Fix blank screen on missing middlewares, by @compulim in PR #3295
• Fixes #3297. Fix className prop is not honored in <ReactWebChat>, by @compulim in PR #3300

Samples

• Resolves #3218 and #2811. Adds documentation on reconnecting to a conversation in minimizable sample, by @corinagum, in PR #3239