Merge pull request #9024 from gyuho/snapshot-doc

clientv3: document context to "Snapshot" API

.words

@@ -34,7 +34,9 @@ prefetching
 protobuf
 prometheus
 repin
+rpc
 serializable
+statusError
 teardown
 too_many_pings
 uncontended

clientv3/maintenance.go

@@ -57,6 +57,8 @@ type Maintenance interface {
 	HashKV(ctx context.Context, endpoint string, rev int64) (*HashKVResponse, error)
 
 	// Snapshot provides a reader for a point-in-time snapshot of etcd.
+	// If the context "ctx" is canceled or timed out, reading from returned
+	// "io.ReadCloser" would error out (e.g. context.Canceled, context.DeadlineExceeded).
 	Snapshot(ctx context.Context) (io.ReadCloser, error)
 
 	// MoveLeader requests current leader to transfer its leadership to the transferee.