CHANGELOG.md: Add timespan reported on empty stores

Signed-off-by: Frederic Branczyk <[email protected]>

CHANGELOG.md

@@ -26,9 +26,9 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 
 - [#2136](https://github.com/thanos-io/thanos/pull/2136) store, compact, bucket: schedule block deletion by adding deletion-mark.json. This adds a consistent way for multiple readers and writers to access object storage.
 Since there are no consistency guarantees provided by some Object Storage providers, this PR adds a consistent lock-free way of dealing with Object Storage irrespective of the choice of object storage. In order to achieve this co-ordination, blocks are not deleted directly. Instead, blocks are marked for deletion by uploading `deletion-mark.json` file for the block that was chosen to be deleted. This file contains unix time of when the block was marked for deletion.
-
 - [#2090](https://github.com/thanos-io/thanos/issues/2090) *breaking* Downsample command: the `downsample` command has moved as the `thanos bucket` sub-command, and cannot be called via `thanos downsample` any more.
 - [#2294](https://github.com/thanos-io/thanos/pull/2294) store: optimizations for fetching postings. Queries using `=~".*"` matchers or negation matchers (`!=...` or `!~...`) benefit the most.
+- [#2310](https://github.com/thanos-io/thanos/pull/2310) query: Report timespan 0 to 0 when discovering no stores.
 
 ## [v0.11.0](https://github.com/thanos-io/thanos/releases/tag/v0.11.0) - 2020.03.02