DEV: rename ReadOnly module to ReadOnlyHeader

lib/read_only_header.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module ReadOnlyHeader
+
+  def check_readonly_mode
+    @readonly_mode = Discourse.readonly_mode?
+  end
+
+  def add_readonly_header
+    response.headers['Discourse-Readonly'] = 'true' if @readonly_mode
+  end
+
+end