remove obsolete comment

src/apphealthmonitor.js

@@ -60,8 +60,6 @@ async function setHealth(app, health) {
     app.healthTime = healthTime;
 }
 
-
-// callback is called with error for fatal errors and not if health check failed
 async function checkAppHealth(app, options) {
     assert.strictEqual(typeof app, 'object');
     assert.strictEqual(typeof options, 'object');