Fix alerts index page headings

gracedb/templates/alerts/index.html

 {% extends "base.html" %}
 
-{% block title %}Options | Notifications{% endblock %}
+{% block title %}Alerts{% endblock %}
 {% block heading %}<!-- leave heading blank -->{% endblock %}
-{% block pageid %}userprofile{% endblock %}
+{% block pageid %}alerts{% endblock %}
 
 {% load static %}
 {% block headcontents %}