Merge "extensions/README.md: add sdk ext v3" into tm-dev am: b63ec41f59 am: 230cab1d4e

Original change: https://googleplex-android-review.googlesource.com/c/platform/prebuilts/sdk/+/18031647

Change-Id: I29759b42e94f33387ab8cd34b72ec6f000b95178
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/extensions/README.md b/extensions/README.md
index 834aafb..dedd59c 100644
--- a/extensions/README.md
+++ b/extensions/README.md
@@ -9,3 +9,4 @@
 
 - 1: Finalized together with Android S / 31 (all modules)
 - 2: Finalized in March 2022 between S and T (mediaprovider, sdkextensions)
+- 3: Finalized together with Android T / 33 (all modules)