Document how to update custom metadata (#101)

Author: maelle

publish/set-up.qmd

@@ -157,6 +157,11 @@ If the metadata contains `review` data then is [shown](https://github.com/r-univ
 
 If useful we could conditionally display other sorts of meta information, [get in touch](https://github.com/r-universe-org/help/discussions).
 
+#### Updating the custom metadata
+
+Please note that the metadata is picked up during the build.
+So if you updated the metadata, you need to trigger a build of the package by doing a commit (or wait for the package to get automatically rebuilt every 30 days)
+
 ## Installing the GitHub app {#appinstall}
 
 Once you pushed your `packages.json` file to your new `universe` repository on GitHub, the next step is to install the [R-universe GitHub app](https://github.com/apps/r-universe/installations/new) on your account.
@@ -246,4 +251,4 @@ You can use a rocket icon as icon.
 ## Removing/deleting an universe
 
 To remove/delete an universe, delete the GitHub repository called `<yourname>.r-universe.dev` from your GitHub account.
-The packages and GitHub integration will automatically get removed within the next R-universe builds.
+The packages and GitHub integration will automatically get removed within the next R-universe builds.