audio_processor: Add README.md

BUG=b:273232671
TEST=None

Change-Id: I93ff658fc19e91487abb5acd1836a482d1b511f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/4334997
Tested-by: ChromeOS Audio Quick Verifier <[email protected]>
Reviewed-by: Chih-Yang Hsia <[email protected]>
Reviewed-by: Curtis Malainey <[email protected]>
Commit-Queue: Li-Yu Yu <[email protected]>
1 file changed