treewide: Fix stale references of Android docs

Commit 9bdf0e8fef86 ("doc: relocate/rename Android README and add BCB
overview") left some obsolete references of Android documents/paths.

This has been pointed out by Sam (thanks!) in:
https://patchwork.ozlabs.org/patch/1104245/#2208134

Fixes: 9bdf0e8fef86 ("doc: relocate/rename Android README and add BCB overview")
Reported-by: Sam Protsenko <semen.protsenko@linaro.org>
Suggested-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
diff --git a/test/py/tests/test_avb.py b/test/py/tests/test_avb.py
index 2bb75ed..8132423 100644
--- a/test/py/tests/test_avb.py
+++ b/test/py/tests/test_avb.py
@@ -8,7 +8,7 @@
 This tests Android Verified Boot 2.0 support in U-boot:
 
 For additional details about how to build proper vbmeta partition
-check doc/README.avb2
+check doc/android/avb2.txt
 
 For configuration verification:
 - Corrupt boot partition and check for failure