docs: add info for events backlog and scope
1. Adds `docker events` description info on the two scope types of events.
2. Adds `docker events` note in two places about backlog limit of event log.
Further info and background info in Issue 727
@@ -31,7 +31,12 @@ Options:
## Description
Use `docker events` to get real-time events from the server. These events differ
-per Docker object type.
+per Docker object type. Different event types have different scopes. Local
+scoped events are only seen on the node they take place on, and swarm scoped
+events are seen on all managers.
+
+Only the last 1000 log events are returned. You can use filters to further limit
+the number of events returned.
### Object types
@@ -160,6 +165,9 @@ that have elapsed since January 1, 1970 (midnight UTC/GMT), not counting leap
seconds (aka Unix epoch or Unix time), and the optional .nanoseconds field is a
fraction of a second no more than nine digits long.
+Only the last 1000 log events are returned. You can use filters to further limit
+the number of events returned.
+
#### Filtering
The filtering flag (`-f` or `--filter`) format is of "key=value". If you would
