android_sdk: Add step to update instructions

capturing other things to update.

Bug: None
Change-Id: I43cdfc6dc4c0771a9fae9b0b17cee30ce3ce8db1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3747161
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1023236}
NOKEYCHECK=True
GitOrigin-RevId: f53a226b036b41f4d553d3da209740dbac7e1e35

README.chromium

diff --git a/README.chromium b/README.chromium
index 93e4a22..1c7a990 100644
--- a/README.chromium
+++ b/README.chromium
@@ -39,3 +39,6 @@
   * Follow the update instructions to get a build from the CI builder.
 * Updating this file:
   * The overall Version field should correspond to the Platform API version.
+* Updating other things:
+  * Use "git log third_party/android_sdk/README.chromium" to find previous
+    update commits and see what sorts of changes to make.