When I showed my reports to Manager level people, they asked if I can have a note or comment for each report which describes them. It makes user understand what the charts inside the report are about...
Come on Power BI! This feature is already available in Power Pivot since 2013: https://support.office.com/en-us/article/Video-Add-descriptions-to-tables-and-columns-in-Power-Pivot-67733153-7ebd-4ae8-9e89-0efb351afd8a
