(PE-1478) Removed redundant docs from existing endpoints
(PE-1478) Corrected existing documentation

- Updated `v2` references to `v3`
- Pluralized endpoint references to HTML docs
- Expanded paging doc file extension
(PE-1478) Document event-counts endpoint
(PE-1478) Fix typo, change "node" to "certname"
Merge pull request #657 from shakedown/dev/burgundy/pe1478-document-event-counts

Dev/burgundy/pe1478 document event counts