Update the maintainer documentation

Author: csouchet

MAINTAINERS.md

@@ -16,6 +16,12 @@ A PR can only be merged into master by a maintainer, if all of these conditions
 
 Maintainers need to perform the following actions **in the order described here** to push out a release.
 
+### Prepare a CRAN submission with R-hub
+
+Before to start a release, verify that the result of `rhub` package is stored in [cran-comments.md](cran-comments.md) (the recent result is on top of the file, and the oldest on the bottom).
+If not, you need to follow this procedure: https://r-hub.github.io/rhub/articles/rhub.html#prepare-a-cran-submission.
+If it's the first time, you launch it on your computer, `rhub` ask you to generate a token, or you can reuse one : https://r-hub.github.io/rhub/reference/validate_email.html.
+
 ### GitHub issues and milestones update
 
 **Note:** we always put issues related to a version in a Milestone whose name matches the version.