Document example for @wrapper & multiple-method interface

[rahulmutt]

No description provided.

[jneira]

Recovering a @rahulmutt gitter message the example could be similar to

• generic

foreign import java unsafe "@wrapper method1,method2" :: ([signature-of-method-one])
                                                      -> ([signature-of-method-two]) -> [jwt]

• for

 public interface SomeInterface {
       String method1(int i);
       double method2(int i, int j);
}

• it would be

foreign import java unsafe "@wrapper method1,method2" :: (Int -> SomeInterface JString)
                                                      -> (Int -> Int -> SomeInterface JDouble) 
                                                      -> SomeInterface

[rahulmutt]

@jneira Looks good! Interested in submitting a PR?

[jneira]

Of course! I'll try to add at the end of section in https://eta-lang.org/docs/user-guides/eta-user-guide/java-interop/java-advanced-ffi#working-with-java-interfaces