Update booleanType docs to only reference non-experiments

Document any side effects to this change:

- some options will be available but not documented. If we choose to
  keep them beyond our initial experiments, we should name them
  appropriately and document them. More than likely they'll be removed
  so not publicly advertising them makes sense unless we want open
  feedback (which we're not looking for yet)

Author: JPrevost

app/graphql/types/query_type.rb

@@ -60,7 +60,8 @@ def record_id(id:, index:)
 
       argument :source, String, required: false, default_value: 'All', deprecation_reason: 'Use `sourceFilter`'
       argument :boolean_type, String, required: false, default_value: 'OR',
-                                      description: 'How to join multiword queries. Defaults to "OR" which means any of the words much match. Options include: "OR", "AND", "minimum_a"'
+                                      description: 'How to join multiword queries. Defaults to "OR" which means any ' \
+                                                   'of the words much match. Options include: "OR", "AND"'
 
       # applied filters
       argument :access_to_files_filter, [String],