[release-v2.6] [DOC] Add 2.6.1 to release notes (#4192)

* [DOC] Add 2.6.1 to release notes (#4191)

(cherry picked from commit e273533)

* Update docs/sources/tempo/release-notes/v2-6.md

---------

Co-authored-by: Kim Nylander <104772500+knylander-grafana@users.noreply.github.com>

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

@@ -98,7 +98,16 @@ This improvement is a result of some of these changes:
 
 ### Other enhancements and improvements
 
-This release also has these notable updates:
+This release also has these notable updates.
+
+#### 2.6.1
+
+* Register gRPC health server to tempo-query. [[PR 4178]](https://github.com/grafana/tempo/pull/4178)
+* Support Tempo on IBM s390x. [[PR 4175]](https://github.com/grafana/tempo/pull/4175)
+* tempo-query: Separate TLS settings for server and client. [[PR 4177]](https://github.com/grafana/tempo/pull/4177)
+* Speedup tempo-query trace search by allowing parallel queries. [[PR 4159]](https://github.com/grafana/tempo/pull/4159)
+
+#### 2.6.0
 
 * Bring back OTel receiver metrics. [[PR 3917](https://github.com/grafana/tempo/pull/3917)]
 * Add a `q` parameter to `/api/v2/search/tags` for tag name filtering. [[PR 3822](https://github.com/grafana/tempo/pull/3822)]
@@ -118,11 +127,15 @@ When [upgrading](https://grafana.com/docs/tempo/latest/setup/upgrade/) to Tempo
 
 We've changed to an RF1 (Replication Factor 1) pattern for TraceQL metrics as we were unable to hit performance goals for RF3 de-duplication. This requires some operational changes to query TraceQL metrics.
 
-TraceQL metrics are still considered experimental. We hope to mark them GA soon when we productionize a complete RF1 write-read path. [PRs [3628](https://github.com/grafana/tempo/pull/3628), [3691]([https://github.com/grafana/tempo/pull/3691](https://github.com/grafana/tempo/pull/3691)), [3723]([https://github.com/grafana/tempo/pull/3723](https://github.com/grafana/tempo/pull/3723)), [3995]([https://github.com/grafana/tempo/pull/3995](https://github.com/grafana/tempo/pull/3995))]
+TraceQL metrics are still considered experimental.
+We hope to mark them GA soon when we productionize a complete RF1 write-read path.
+[PRs [3628](https://github.com/grafana/tempo/pull/3628), [3691]([https://github.com/grafana/tempo/pull/3691](https://github.com/grafana/tempo/pull/3691)), [3723]([https://github.com/grafana/tempo/pull/3723](https://github.com/grafana/tempo/pull/3723)), [3995]([https://github.com/grafana/tempo/pull/3995](https://github.com/grafana/tempo/pull/3995))]
 
 **For recent data**
 
-The local-blocks processor must be enabled to start using metrics queries like `{ } | rate()`. If not enabled metrics queries fail with the error `localblocks processor not found`. Enabling the local-blocks processor can be done either per tenant or in all tenants.
+The local-blocks processor must be enabled to start using metrics queries like `{ } | rate()`.
+If not enabled metrics queries fail with the error `localblocks processor not found`.
+Enabling the local-blocks processor can be done either per tenant or in all tenants.
 
 * Per-tenant in the per-tenant overrides:
 
@@ -223,10 +236,20 @@ Storage:<br />
   </tr>
 </table>
 
+### Other breaking changes
+
+* **BREAKING CHANGE** tempo-query is no longer a Jaeger instance with grpcPlugin. It's now a standalone server. Serving a gRPC API for Jaeger on `0.0.0.0:7777` by default. [[PR 3840]](https://github.com/grafana/tempo/issues/3840)
+
 ## Bugfixes
 
 For a complete list, refer to the [Tempo changelog](https://github.com/grafana/tempo/releases).
 
+### 2.6.1
+
+* Bring back application-json content-type header. [[PR 4123]](https://github.com/grafana/tempo/pull/4123)
+
+### 2.6.0
+
 * Fix panic in certain metrics queries using `rate()` with `by`. [[PR 3847](https://github.com/grafana/tempo/pull/3847)]
 * Fix metrics queries when grouping by attributes that may not exist. [[PR 3734](https://github.com/grafana/tempo/pull/3734)]
 * Fix metrics query histograms and quantiles on `traceDuration`. [[PR 3879](https://github.com/grafana/tempo/pull/3879)]