[DOCS] Add steps for Docker image verification (#158303)

This adds steps to the [Install Kibana with
Docker](https://www.elastic.co/guide/en/kibana/current/docker.html) page
for verifying the downloaded Docker images. I split apart the original
version which had all the commands in one block. Having them separate
allows us to add in the optional "verify images" step with a link to the
Elasticsearch docs for additional info.

Rel: https://github.com/elastic/dev/issues/2002

**Preview**

---
![Screenshot 2023-05-23 at 1 56 32
PM](7d35b9ad-d0f1-4c01-b26b-6ca469fdc644)

---

![Screenshot 2023-05-23 at 1 47 24
PM](0ec110be-1560-4dcc-8949-792e09846ee9)

---------

Co-authored-by: Tiago Costa <tiago.costa@elastic.co>

docs/setup/docker.asciidoc

@@ -34,13 +34,39 @@ endif::[]
 
 ifeval::["{release-state}"!="unreleased"]
 
+.. Create a new Docker network for {es} and {kib}:
++
 [source,sh,subs="attributes"]
 ----
 docker network create elastic
+----
+
+.. Pull the {es} Docker image:
++
+[source,sh,subs="attributes"]
+----
 docker pull {es-docker-image}
+----
+
+.. Optional: Verify the {es} Docker image signature::
++
+[source,sh,subs="attributes"]
+----
+wget https://artifacts.elastic.co/cosign.pub
+cosign verify --key cosign.pub {docker-repo}:{version}
+----
++
+For details about this step, refer to {ref}/docker.html#docker-verify-signature[Verify the {es} Docker image signature] in the {es} documentation.
+
+.. Start {es} in Docker:
++
+[source,sh,subs="attributes"]
+----
 docker run --name es-node01 --net elastic -p 9200:9200 -p 9300:9300 -t {es-docker-image}
 ----
 
+
+
 endif::[]
 
 --
@@ -79,6 +105,34 @@ docker pull {docker-image}
 docker run --name kib-01 --net elastic -p 5601:5601 {docker-image}
 ----
 
+.. Pull the {kib} Docker image:
++
+[source,sh,subs="attributes"]
+----
+docker pull {docker-image}
+----
+
+.. Optional: Verify the {kib} Docker image signature::
++
+[source,sh,subs="attributes"]
+----
+wget https://artifacts.elastic.co/cosign.pub
+cosign verify --key cosign.pub {docker-repo}:{version}
+----
++
+For details about this step, refer to {ref}/docker.html#docker-verify-signature[Verify the {es} Docker image signature] in the {es} documentation.
+
+.. Start {kib} in Docker:
++
+[source,sh,subs="attributes"]
+----
+docker run --name kib-01 --net elastic -p 5601:5601 {docker-image}
+----
+
+
+
+
+
 endif::[]
 --
 +