Update note rendering with new GitHub callouts

https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#alerts

Author: SimonMarquis

README.md

@@ -140,7 +140,8 @@ The baseline profile for this app is located at [`app/src/main/baseline-prof.txt
 It contains rules that enable AOT compilation of the critical user path taken during app launch.
 For more information on baseline profiles, read [this document](https://developer.android.com/studio/profile/baselineprofiles).
 
-> Note: The baseline profile needs to be re-generated for release builds that touch code which changes app startup.
+> [!NOTE]
+> The baseline profile needs to be re-generated for release builds that touch code which changes app startup.
 
 To generate the baseline profile, select the `benchmark` build variant and run the
 `BaselineProfileGenerator` benchmark test on an AOSP Android Emulator.