DEV: Add short explanations for the core features specs

Author: Flink

spec/system/core_features_spec.rb

@@ -1,5 +1,21 @@
 # frozen_string_literal: true
 
+# Parts of the core features examples can be skipped like so:
+#   it_behaves_like "having working core features", skip_examples: %i[login likes]
+#
+# List of keywords for skipping examples:
+# - login
+# - likes
+# - profile
+# - topics
+# - topics:read
+# - topics:reply
+# - topics:create
+# - search
+# - search:quick_search
+# - search:full_page
+#
+# For more details, see https://meta.discourse.org/t/-/361381
 RSpec.describe "Core features", type: :system do
   before { enable_current_plugin }