remove ubuntu 18.04 from examples

Ubuntu 18.04 reached end of standard support, so remove it from examples
in our docs.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

compose/compose-file/compose-file-v2.md

@@ -856,7 +856,7 @@ a partial image ID.
 image: redis
 ```
 ```yaml
-image: ubuntu:18.04
+image: ubuntu:22.04
 ```
 ```yaml
 image: tutum/influxdb

compose/compose-file/compose-file-v3.md

@@ -805,7 +805,7 @@ services:
       placement:
         constraints:
           - "node.role==manager"
-          - "engine.labels.operatingsystem==ubuntu 18.04"
+          - "engine.labels.operatingsystem==ubuntu 22.04"
         preferences:
           - spread: node.labels.zone
 ```
@@ -1302,7 +1302,7 @@ a partial image ID.
 image: redis
 ```
 ```yaml
-image: ubuntu:18.04
+image: ubuntu:22.04
 ```
 ```yaml
 image: tutum/influxdb

develop/develop-images/dockerfile_best-practices.md

@@ -24,7 +24,8 @@ changes from the previous layer. The following is the contents of an example Doc
 
 ```dockerfile
 # syntax=docker/dockerfile:1
-FROM ubuntu:18.04
+
+FROM ubuntu:22.04
 COPY . /app
 RUN make /app
 CMD python /app/app.py
@@ -32,7 +33,7 @@ CMD python /app/app.py
 
 Each instruction creates one layer:
 
-- `FROM` creates a layer from the `ubuntu:18.04` Docker image.
+- `FROM` creates a layer from the `ubuntu:22.04` Docker image.
 - `COPY` adds files from your Docker client's current directory.
 - `RUN` builds your application with `make`.
 - `CMD` specifies what command to run within the container.
@@ -448,7 +449,8 @@ subsequent `apt-get install` instructions fail. For example, the issue will occu
 
 ```dockerfile
 # syntax=docker/dockerfile:1
-FROM ubuntu:18.04
+
+FROM ubuntu:22.04
 RUN apt-get update
 RUN apt-get install -y curl
 ```
@@ -458,7 +460,8 @@ modify `apt-get install` by adding an extra package as shown in the following Do
 
 ```dockerfile
 # syntax=docker/dockerfile:1
-FROM ubuntu:18.04
+
+FROM ubuntu:22.04
 RUN apt-get update
 RUN apt-get install -y curl nginx
 ```
@@ -890,4 +893,3 @@ These Official Images have exemplary Dockerfiles:
 * [Guidelines for Creating Docker Official Images](../../docker-hub/official_images.md)
 * [Best practices to containerize Node.js web applications with Docker](https://snyk.io/blog/10-best-practices-to-containerize-nodejs-web-applications-with-docker){:target="_blank" rel="noopener" class="_"}
 * [More about Base Images](../../build/building/base-images.md)
-

storage/storagedriver/index.md

@@ -39,7 +39,8 @@ read-only. Consider the following Dockerfile:
 
 ```dockerfile
 # syntax=docker/dockerfile:1
-FROM ubuntu:18.04
+
+FROM ubuntu:22.04
 LABEL org.opencontainers.image.authors="org@example.com"
 COPY . /app
 RUN make /app
@@ -48,7 +49,7 @@ CMD python /app/app.py
 ```
 
 This Dockerfile contains four commands. Commands that modify the filesystem create
-a layer. The `FROM` statement starts out by creating a layer from the `ubuntu:18.04`
+a layer. The `FROM` statement starts out by creating a layer from the `ubuntu:22.04`
 image. The `LABEL` command only modifies the image's metadata, and does not produce
 a new layer. The `COPY` command adds some files from your Docker client's current
 directory. The first `RUN` command builds your application using the `make` command,
@@ -157,14 +158,15 @@ usually `/var/lib/docker/` on Linux hosts. You can see these layers being pulled
 in this example:
 
 ```console
-$ docker pull ubuntu:18.04
-18.04: Pulling from library/ubuntu
+$ docker pull ubuntu:22.04
+22.04: Pulling from library/ubuntu
 f476d66f5408: Pull complete
 8882c27f669e: Pull complete
 d9af21273955: Pull complete
 f5029279ec12: Pull complete
-Digest: sha256:ab6cb8de3ad7bb33e2534677f865008535427390b117d7939193f8d1a6613e34
-Status: Downloaded newer image for ubuntu:18.04
+Digest: sha256:6120be6a2b7ce665d0cbddc3ce6eae60fe94637c6a66985312d1f02f63cc0bcd
+Status: Downloaded newer image for ubuntu:22.04
+docker.io/library/ubuntu:22.04
 ```
 
 Each of these layers is stored in its own directory inside the Docker host's