fix image links in getting started (grafana#11478)

Fixes two image links as images aren't showing up from previous PR
(grafana#11350).

https://grafana.com/docs/loki/next/get-started/quick-start/ should
display a graphic and a screenshot of Grafana Explore, but only the
captions are visible.

docs/sources/get-started/quick-start.md

@@ -19,7 +19,7 @@ The Docker Compose configuration instantiates the following components, each in
 - **Minio** an S3-compatible object store which Loki uses to store its index and chunks.
 - **Grafana** which provides visualization of the log lines captured within Loki.
 
-![Getting started sample application](get-started-flog.png)
+{{< figure max-width="75%" src="/media/docs/loki/get-started-flog.png" caption="Getting started sample application" alt="Getting started sample application">}}
 
 ## Installing Loki and collecting sample logs
 
@@ -80,7 +80,7 @@ Once you have collected logs, you will want to view them.  You can view your log
 
     The test environment includes [Grafana](https://grafana.com/docs/grafana/latest/), which you can use to query and observe the sample logs generated by the flog application.  You can access the Grafana cluster by navigating to [http://localhost:3000](http://localhost:3000).  The Grafana instance provided with this demo has a Loki [datasource](https://grafana.com/docs/grafana/latest/datasources/loki/) already configured.
 
-![Grafana Explore](grafana-query-builder.png)
+{{< figure src="/media/docs/loki/grafana-query-builder.png" caption="Query builder in Grafana Explore" alt="Grafana Explore">}}
 
 1. From the Grafana main menu, click the **Explore** icon (1) to launch the Explore tab. To learn more about Explore, refer the [Explore](https://grafana.com/docs/grafana/latest/explore/) documentation.