[ADD] Demographic survey.

_site/index.html.j2

@@ -102,7 +102,7 @@
 					<h4>Dates: {{dates}}</h4>
 					<h4>Costs: {{details.costs}}</h4>
 					<h4>Location: <a href="{{location_url}}">{{location_name}}</a></h4>
-                    <h4>Note: Make sure to read the <a href="{{code_of_conduct_link}}">code of conduct</a> of BrainHack Global.</h4>
+                    <h4>Note: Make sure to read the <a href="{{code_of_conduct_link}}">code of conduct</a> of BrainHack Global and fill out the <a href="{{survey_link}}" target="_blank">demographic survey</a>.</h4>
                     <br>
 					<p class="text-center">Please join the <a href="{{mattermost_link}}" target="_blank">Brainhack Mattermost</a> for updated information on the developing Hackathon content and to contribute your own ideas.</p>
                 </div>

data.json

@@ -12,6 +12,7 @@
   },
   "code_of_conduct_link": "https://brainhack.org/code-of-conduct.html",
   "registration_link": "https://www.eventbrite.ca/e/brainhack-montreal-2023-tickets-743618842977",
+  "survey_link": "https://forms.gle/E53wHxV3jLi79tmX7",
   "mattermost_link": "https://mattermost.brainhack.org/brainhack/channels/brainhack-global-mtl",
   "project_link": "https://brainhack.org/global2023/projects/",
   "project_submit_link": "https://github.com/brainhackorg/global2023/issues/new?assignees=&labels=project&template=project-submission-template.yml",