Add ability to pass flag read only status to aapt2

Also adds the ability to pass flags to the compile command

Test: automated
Bug: 344979955
Flag: EXEMPT tools change
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:b5c0ef0843f1426b9237b050994e8753b0921617)
Merged-In: I29997712d262be6d89eef16daf67d37cbafe3cba
Change-Id: I29997712d262be6d89eef16daf67d37cbafe3cba
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index 8fe414f..2f17853 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -332,8 +332,9 @@
     AddOptionalSwitch("-v", "Enables verbose logging.", &verbose_);
     AddOptionalFlagList("--feature-flags",
                         "Specify the values of feature flags. The pairs in the argument\n"
-                        "are separated by ',' and the name is separated from the value by '='.\n"
-                        "Example: \"flag1=true,flag2=false,flag3=\" (flag3 has no given value).",
+                        "are separated by ',' the name is separated from the value by '='.\n"
+                        "The name can have a suffix of ':ro' to indicate it is read only."
+                        "Example: \"flag1=true,flag2:ro=false,flag3=\" (flag3 has no given value).",
                         &feature_flags_args_);
     AddOptionalSwitch("--non-updatable-system",
                       "Mark the app as a non-updatable system app. This inserts\n"