Document "feature_flags" argument.

PiperOrigin-RevId: 925535890
Change-Id: Ib642457bc16016d5fe7261ccdda8ddf13a60129d

rules/resources.bzl

diff --git a/rules/resources.bzl b/rules/resources.bzl
index e3dea32..01adcfb 100644
--- a/rules/resources.bzl
+++ b/rules/resources.bzl
@@ -569,6 +569,7 @@
         generally only desirable for test targets that aren't potentially
         running compile-time optimizations.
       generate_out_symbols: boolean. Whether to generate the merged symbols binary file.
+      feature_flags: string. The string value for --feature-flags to pass to aapt2.
       crunch_png: boolean. Determines whether `aapt2 compile` should crunch PNG files.
       aapt: FilesToRunProvider. The aapt executable or FilesToRunProvider.
       has_local_proguard_specs: If the target has proguard specs.