(doc) notes on when deployments happen

Author: dummdidumm

docs/internal/deployment.md

@@ -7,3 +7,8 @@ The [publisher is Svelte](https://marketplace.visualstudio.com/manage/publishers
 ### npm deployments
 
 - Deployments come from a bot: `svelte-language-tools-deploy`
+
+### When Deployments happen
+
+- Nightly builds are triggered through a scheduled GitHub workflow every night at 04:00 UTC.
+- Production builds are triggered by creating a new tag, which is best done through the "do a release" on Github. The tag name equals the version that is then shown on the marketplace, so each tag should have a higher version than the previous.