Remove done items from the roadmap

content/docs/introduction/roadmap.md

@@ -11,35 +11,6 @@ features and current work, see the issue trackers for the various repositories,
 for example, the [Prometheus
 server](https://github.com/prometheus/prometheus/issues).
 
-### New storage engine
-
-A new more efficient storage engine is in development. It will offer reduced
-resource usage, better inverted indexes, and generally allow Prometheus to
-scale further.
-
-### Long-term storage
-
-Currently Prometheus has support for storing samples on local disk, as well as
-experimental support for sending data into remote systems via a generic mechanism.
-Example receivers exist for a [variety of TSDBs](https://github.com/prometheus/prometheus/tree/master/documentation/examples/remote_storage).
-
-We plan to add read-back support from other TSDBs via a generic mechanism in Prometheus,
-such as [Cortex](https://github.com/weaveworks/cortex).
-
-GitHub issue: [#10](https://github.com/prometheus/prometheus/issues/10)
-
-### Improved staleness handling
-
-Currently Prometheus omits time series from query results if the timestamp for
-which the query is executed is more than 5 minutes away from the nearest
-sample. This means that time series will grow "stale" in instant queries after
-not receiving samples for 5 minutes. This currently prevents usage of
-client-side timestamps from the Pushgateway or CloudWatch Exporter, which might
-indicate a time more than 5 minutes in the past. We plan on only considering a
-time series stale if it was not present in the most recent scrape.
-
-GitHub issue: [#398](https://github.com/prometheus/prometheus/issues/398)
-
 ### Server-side metric metadata support
 
 At this time, metric types and other metadata are only used in the