[HOWTO] Use the Tasks App

I think a “current limitations” or “known bugs” section is warranted for Tasks, as at least 2 users in this thread struggled with getting newly created or renamed task-categories/-lists from the remote onto their device. @Manoj, are you fine with me editing this in?

When users rename the task-category (a calendar basically), the new task-list-title currently isn’t synced implicitly back to the device but needs manual intervention. This came up recently at Tasks titles fail to sync between Murena Cloud and phone app - #13 by tcecyk

There’s no gitlab backlog issue yet on this, but upstream there is talk at https://github.com/dmfs/opentasks/issues/313#issuecomment-1372981304