Draft of release notes for loki 2.6. (#6546) (#6624)

* Draft of release notes for loki 2.6.

* Apply suggestions from code review

Adding Karen's suggestions.

Co-authored-by: Karen Miller <[email protected]>

Co-authored-by: Karen Miller <[email protected]>
(cherry picked from commit 53a89e2)

Co-authored-by: Jennifer Villa <[email protected]>

Author: slim-bean

docs/sources/release-notes/v2-6.md

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+---
+title: V2.6
+weight: 66
+---
+
+# Version 2.6 release notes
+
+Grafana Labs is excited to announce the release of Loki 2.6. Here's a summary of new enhancements and important fixes.
+
+## Features and enhancements
+
+- **Query multiple tenants at once.** We've introduced cross-tenant query federation, which allows you to issue one query to multiple tenants and get a single, consolidated result. This is great for scenarios where you need a global view of logs within your multi-tenant cluster. For more information on how to enable this feature, see [Multi-Tenancy]({{< relref "../operations/multi-tenancy.md" >}}). 
+- **Filter out and delete certain log lines from query results.** This is particularly useful in cases where users may accidentally write sensitive information to Loki that they do not want exposed. Users craft a LogQL query that selects the specific lines they're interested in, and then can choose to either filter out those lines from query results, or permanently delete them from Loki's storage. For more information, see [Logs Deletion]({{< relref "../operations/storage/logs-deletion.md" >}}).
+- **Improved query performance on instant queries.** Loki now splits instant queries with a large time range (for example, `sum(rate({app="foo"}[6h]))`) into several smaller sub-queries and executes them in parallel. Users don't need to take any action to enjoy this performance improvement; however, they can adjust the number of sub-queries generated by modifying the `split_queries_by_interval` configuration parameter, which currently defaults to `30m`. 
+- **Support Baidu AI Cloud as a storage backend.** Loki users can now use Baidu Object Storage (BOS) as their storage backend. See [bos_storage_config]({{< relref "../configuration/_index.md#bos_storage_config" >}}) for details. 
+
+For a full list of all changes please look at the [CHANGELOG](https://github.com/grafana/loki/blob/main/CHANGELOG.md).
+
+## Upgrade Considerations
+
+As always, please read the [upgrade guide](../../upgrading/#260) before upgrading Loki.
+
+## Bug fixes
+
+### 2.6.0 bug fixes
+
+V2.6.0 fixes numerous bugs. The [CHANGELOG](https://github.com/grafana/loki/blob/main/CHANGELOG.md) has the complete list.
+
+A summary of some of the more important fixes:
+
+- [PR 6152](https://github.com/grafana/loki/pull/6152) Fixed a scenario where live tailing of logs could cause unbounded ingester memory growth. 
+- [PR 5685](https://github.com/grafana/loki/pull/5685) Fixed a bug in Loki's push request parser that allowed users to send arbitrary non-string data as a log line. We now test that the pushed values are valid strings and return an error if values are not valid strings.
+- [PR 5799](https://github.com/grafana/loki/pull/5799) Fixed incorrect deduplication logic for cases where multiple log entries with the same timestamp exist. 
+- [PR 5888](https://github.com/grafana/loki/pull/5888) Fixed a bug in the [common configuration]({{< relref "../configuration/_index.md#common" >}}) where the `instance_interface_names` setting was getting overwritten by the default ring configuration.