Update index.md

Fixes two typos and a minor inconsistency

updates to whats new doc, and building from source, also small fix for panel snapshot, single panelsnapshot should expand panel span to 12

Update gettingstarted.md

Update admin.md

Update influxdb.md

fleshed out 'getting started' text

Enabled snapshot sharing of single panels, enabled sharing of snapshot dashboards (but you cannot snapshot a snapshot

clarified some language, split into influx 0.9 and influx 0.8 since they are now two separate datasources/queryeditors

Updates to migration doc