Added update road map step to release checklist

relates to #9232

Signed-off-by: Jonas Helming <[email protected]>

doc/Publishing.md

@@ -147,3 +147,7 @@ To successfully complete a `yarn upgrade`, one must:
 
 * Close current release [milestone](https://github.com/eclipse-theia/theia/milestones).
 * Create the next two milestones in the case they do not already exist. Generally, the release is performed on the last Thursday of the month, but there may be exceptions (bug fix release, holidays, etc.)
+
+### Update Roadmap
+* If the current release is the last in a quarter, ask the team to update the [roadmap](https://github.com/eclipse-theia/theia/wiki/Roadmap) of the past quarter (close, remove or move items)
+* If the current release is the second in a quarter, create [roadmap template](https://github.com/eclipse-theia/theia/wiki/Roadmap) for the next quarter, ask the team to contribute to it and add it to the agenda of the Theia dev meeting