Fix docs for `push_result`

[ci skip]

lib/gitlab/markdown/reference_filter.rb

@@ -40,7 +40,7 @@ module Gitlab
       # Add a reference to the pipeline's result Hash
       #
       # type   - Singular Symbol reference type (e.g., :issue, :user, etc.)
-      # value - Object to add
+      # values - One or more Objects to add
       def push_result(type, *values)
         return if values.empty?