Update feature spec

Author: bsatarnejad

test/components/primer/open_project/page_header_test.rb

@@ -340,7 +340,7 @@ def test_raises_if_actions_have_different_sizes
     end
 
     assert_equal(
-      "PageHeader actions must all use the same size. Set the same `size:` for every action (or omit it to use :medium everywhere).",
+      "PageHeader button actions must all use the same size. Set the same `size:` for every button-like action (or omit it to use :medium everywhere).",
       err.message
     )
   end