Docs: Add info about logs/metrics unification to What's New docs (#26325)

* Docs: Add info about logs/metrics unification to What's New docs

* Apply suggestions from code review

Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>

docs/sources/guides/whats-new-in-v7-1.md

@@ -23,6 +23,7 @@ The main highlights are:
 - [**Deep linking for Google Cloud Monitoring (formerly named Google Stackdriver) datasource**]({{< relref "#deep-linking-for-google-cloud-monitoring-formerly-named-google-stackdriver-datasource" >}})
 - [**Transforms**]({{< relref "#transforms" >}})
 - [**Stat panel text mode**]({{< relref "#stat-panel-text-mode" >}})
+- [**Unification of Explore modes**]({{< relref "#explore-modes-unified" >}})
 - [**Grafana Enterprise features**]({{< relref "#grafana-enterprise-features" >}})
   - [**Support for HashiCorp Vault**]({{< relref "#support-for-hashicorp-vault" >}})
   - [**Internal links for Elastic**]({{< relref "#internal-links-for-elastic" >}})
@@ -73,6 +74,12 @@ You can use the Text mode option to control what text the panel renders. If the
 
 {{< docs-imagebox img="/img/docs/v71/stat-panel-text-modes.png" max-width="1025px" caption="Stat panel" >}}
 
+## Explore modes unified
+
+Grafana 7.1 includes a major change to Explore: it removes the query mode selector.
+
+Many data sources tell Grafana whether a response contains time series data or logs data. Using this information, Explore chooses which visualization to use for that data. This means that you don't need to switch back and forth between Logs and Metrics modes depending on the type of query that you want to make. 
+
 ## Grafana Enterprise features
 
 General features are included in the Grafana Enterprise edition software.