add the /version endpoint to the API docs

I had to find this by accident. It should be documented here.
Adds units of time to flag docs

This fixes issue #905 based on the comments provided in server/cluster_config.go
Merge pull request #907 from MattParker89/patch-1

Adds units of time to flag docs
Merge pull request #882 from cap10morgan/patch-1

add the /version endpoint to the API docs
fix(docs/api): mention version endpoint is per instance
CHANGELOG: v0.4.6
server: bump to 0.4.6+git