add scope note in moviegoer (#1834)

This is consistent with  Simple Calculator.

Author: VaiaPatta1985

exercises/concept/moviegoer/.docs/instructions.md

@@ -42,8 +42,7 @@ Members get free popcorn when they watch any movie.
 
 Implement the `Moviegoer.claim_free_popcorn!` method.
 If a viewer is a movie club member, they should be rewarded with their free popcorn.
-If they are not, the method should raise the `NotMovieClubMemberError` exception defined at the top of the code.
-
+If they are not, the method should raise the `UnsupportedOperation` exception defined at the top of the code.
 
 ```ruby
 Moviegoer.new(21, member: true).claim_free_popcorn!
@@ -52,3 +51,7 @@ Moviegoer.new(21, member: true).claim_free_popcorn!
 Moviegoer.new(17, member: false).claim_free_popcorn!
 #=> Exception was raised! (NotMovieClubMemberError)
 ```
+
+~~~~exercism/note
+In this exercise, you are expected to define the `UnsupportedOperation` exception for a specific scope.
+~~~~