Link to the backend deploy instructions

Author: adamnovak

deploy.md

@@ -1,5 +1,7 @@
 ### Deploying the frontend for the demo on github pages
 
+> To update the *backend*, see the [wiki](https://github.com/vgteam/sequenceTubeMap/wiki/Deploying-the-Tube-Map).
+
 Here are the steps to deploy an update to the demo at [https://vgteam.github.io/sequenceTubeMap/](https://vgteam.github.io/sequenceTubeMap/). It updates the `gh-pages` branch of the github repo, which is the source for the demo website.
 
 - Add the following line to `package.json`:
@@ -18,3 +20,4 @@ Here are the steps to deploy an update to the demo at [https://vgteam.github.io/
 - Run `yarn run predeploy` followed by `yarn run deploy`.
 
 In theory, the same commands should work when using `npm` instead of `yarn`, but I was told that deployment of the `gh-pages` branch fails at least with some versions of `npm` and `node`.
+