Tidy up m2r formatting of geopm_report.7 and add notes on aggregation
Tidy up m2r formatting of geopm_report.7 and add notes on aggregation

- m2r: unnecessary token separators, malformed tables, malformed code
  snippets, html-specific cross-references
- aggregation: separately discuss time- and domain-aggregation

geopm/geopm,cmcantalupo/geopm,cmcantalupo/geopm,geopm/geopm,geopm/geopm,cmcantalupo/geopm,geopm/geopm,geopm/geopm,cmcantalupo/geopm,cmcantalupo/geopm