Update readme: fix link to Issue Board

README.md

 # Indienet Plans
 
-This project’s [Issue Board](boards/) is used for planning and project managing the Indienet project in general.
+This project’s [Issue Board](https://source.ind.ie/indienet/plans/boards) is used for planning and project managing the Indienet project in general.
 
 Specific sub-project repositories, when they exist, will be used to manage the issues for those sub-projects.