Docs: add missing alt text (1/3) (#79274)

* Added missing alt text

* Reworded text

docs/sources/whatsnew/whats-new-in-v10-2.md

@@ -327,7 +327,7 @@ The **Add field from calculation** transformation has been updated.
 - **Floor (floor)** - Returns the largest integer less than or equal to a given expression.
 - **Ceiling (ceil)** - Returns the smallest integer greater than or equal to a given expression.
 
-{{< figure src="/media/docs/grafana/transformations/unary-operation.png" >}}
+{{< figure src="/media/docs/grafana/transformations/unary-operation.png" alt="Unary operation options" >}}
 
 Also, **Row index** can now show the index as a percentage.
 

docs/sources/whatsnew/whats-new-in-v7-2.md

@@ -132,7 +132,7 @@ A new layout option is available when rendering reports: the grid layout. With t
 
 The grid layout is also available for the [Export dashboard as PDF]({{< relref "../dashboards/share-dashboards-panels#export-dashboard-as-pdf" >}}) feature.
 
-{{< figure src="/static/img/docs/enterprise/reports_grid_landscape_preview.png" max-width="500px" class="docs-image--no-shadow" >}}
+{{< figure src="/static/img/docs/enterprise/reports_grid_landscape_preview.png" max-width="500px" class="docs-image--no-shadow" alt="Report in grid layout" >}}
 
 ### Report time range
 

docs/sources/whatsnew/whats-new-in-v7-4.md

@@ -169,7 +169,7 @@ Many thanks to [mtanda](https://github.com/mtanda) this contribution!
 
 Google Cloud Monitoring data source ships with pre-configured dashboards for some of the most popular GCP services. These curated dashboards are based on similar dashboards in the GCP dashboard samples repository. In this release, we have expanded the set of pre-configured dashboards.
 
-{{< figure src="/static/img/docs/google-cloud-monitoring/curated-dashboards-7-4.png" max-width= "650px" >}}
+{{< figure src="/static/img/docs/google-cloud-monitoring/curated-dashboards-7-4.png" max-width= "650px" alt="Google Cloud Monitoring pre-configured dashboards" >}}
 
 If you want to customize a dashboard, we recommend that you save it under a different name. Otherwise the dashboard will be overwritten when a new version of the dashboard is released.