Added YARD annotations to ByApprovalsFinder and improved documentation

ee/app/finders/merge_requests/by_approvals_finder.rb

 # frozen_string_literal: true
 
 module MergeRequests
-  # Used to filter MergeRequests collections by approvers
+  # Used to filter MergeRequest collections by approvers
   class ByApprovalsFinder
     attr_reader :usernames, :ids
 
     # We apply a limitation to the amount of elements that can be part of the filter condition
     MAX_FILTER_ELEMENTS = 5
 
-    # rubocop:disable CodeReuse/ActiveRecord
+    # Initialize the finder
+    #
+    # @param [Array<String>] usernames
+    # @param [Array<Integers>] ids
     def initialize(usernames, ids)
+      # rubocop:disable CodeReuse/ActiveRecord
       @usernames = Array(usernames).map(&:to_s).uniq.take(MAX_FILTER_ELEMENTS)
       @ids = Array(ids).uniq.take(MAX_FILTER_ELEMENTS)
+      # rubocop:enable CodeReuse/ActiveRecord
     end
-    # rubocop:enable CodeReuse/ActiveRecord
 
+    # Filter MergeRequest collections by approvers
+    #
+    # @param [ActiveRecord::Relation] items the activerecord relation
     def execute(items)
       if by_no_approvals?
         without_approvals(items)
@@ -32,25 +39,37 @@ module MergeRequests
     private
 
     # Is param using special condition: "None" ?
+    #
+    # @return [Boolean] whether special condition "None" is being used
     def by_no_approvals?
-      includes_custom_label?(IssuableFinder::FILTER_NONE)
+      includes_special_label?(IssuableFinder::FILTER_NONE)
     end
 
     # Is param using special condition: "Any" ?
+    #
+    # @return [Boolean] whether special condition "Any"" is being used
     def by_any_approvals?
-      includes_custom_label?(IssuableFinder::FILTER_ANY)
+      includes_special_label?(IssuableFinder::FILTER_ANY)
     end
 
-    def includes_custom_label?(label)
+    # Check if we have the special label in ids or usernames field
+    #
+    # @param [String] label the special label
+    # @return [Boolean] whether ids or usernames includes the special label
+    def includes_special_label?(label)
       ids.first.to_s.downcase == label || usernames.map(&:downcase).include?(label)
     end
 
     # Merge Requests without any approval
+    #
+    # @param [ActiveRecord::Relation] items
     def without_approvals(items)
       items.without_approvals
     end
 
     # Merge Requests with any number of approvals
+    #
+    # @param [ActiveRecord::Relation] items the activerecord relation
     def with_any_approvals(items)
       items.select_from_union([
         items.with_approvals
@@ -58,11 +77,15 @@ module MergeRequests
     end
 
     # Merge Requests approved by given usernames
+    #
+    # @param [ActiveRecord::Relation] items the activerecord relation
     def find_approved_by_names(items)
       items.approved_by_users_with_usernames(*usernames)
     end
 
     # Merge Requests approved by given user IDs
+    #
+    # @param [ActiveRecord::Relation] items the activerecord relation
     def find_approved_by_ids(items)
       items.approved_by_users_with_ids(*ids)
     end