Update key layout docs to include `key usage` syntax

Change-Id: If3cdd4dfd889b9e5ceebf4582db6a3775ab43355
1 file changed
tree: d79a535cd150bd3dc040a117436456a2efa1e2d7
  1. scripts/
  2. src/
  3. templates/
  4. .gitignore
  5. CleanSpec.mk
  6. README