Adds 403 response if PDF export is disabled

lib/response.js

@@ -384,7 +384,12 @@ function noteActions (req, res, next) {
         actionInfo(req, res, note)
         break
       case 'pdf':
+        if (config.allowpdfexport) {
           actionPDF(req, res, note)
+        } else {
+          logger.error('PDF export failed: Disabled by config. Set "allowpdfexport: true" to enable. Check the documentation for details')
+          response.errorForbidden(res)
+        }
         break
       case 'gist':
         actionGist(req, res, note)