README.md in rubocop-ast-0.2.0 vs README.md in rubocop-ast-0.3.0

@@ -33,11 +33,12 @@
 
 See the [docs site](https://docs.rubocop.org/rubocop-ast) for more details.
 
 ### Parser compatibility switches
 
-The main `RuboCop` gem uses [legacy AST output from parser](https://github.com/whitequark/parser/#usage).
-This gem is meant to be compatible with all settings. For example, to have `-> { ... }` emitted
+This gem, by default, uses most [legacy AST output from parser](https://github.com/whitequark/parser/#usage), except for `emit_forward_arg` which is set to `true`.
+
+The main `RuboCop` gem uses these defaults (and is currently only compatible with these), but this gem can be used separately from `RuboCop` and is meant to be compatible with all settings. For example, to have `-> { ... }` emitted
 as `LambdaNode` instead of `SendNode`:
 
 ```ruby
 RuboCop::AST::Builder.emit_lambda = true
 ```