Update error message for easier error resolution

Update the error message of file_list_diff tool for users to resolve
the errors easily.
Also, add comments to classify the modules in the allowlist.

Bug: 368185982
Test: m

Change-Id: Id9925f700c48894f073157b6187d5aa4bde78398
diff --git a/tools/filelistdiff/allowlist b/tools/filelistdiff/allowlist
index e7b1d01..e215b22 100644
--- a/tools/filelistdiff/allowlist
+++ b/tools/filelistdiff/allowlist
@@ -1,12 +1,14 @@
 # Known diffs only in the KATI system image
-etc/NOTICE.xml.gz
 framework/oat/x86_64/apex@com.android.compos@javalib@service-compos.jar@classes.odex
 framework/oat/x86_64/apex@com.android.compos@javalib@service-compos.jar@classes.odex.fsv_meta
 framework/oat/x86_64/apex@com.android.compos@javalib@service-compos.jar@classes.vdex
 framework/oat/x86_64/apex@com.android.compos@javalib@service-compos.jar@classes.vdex.fsv_meta
 
+# Known diffs that are installed in either system image with the configuration
 # b/353429422
 init.environ.rc
+# b/338342381
+etc/NOTICE.xml.gz
 
 # Known diffs only in the Soong system image
 lib/libhidcommand_jni.so