Add a note about Ubuntu 18 deprecation (#29527)

Co-authored-by: Dusko Dobranic <101048884+ddobranic@users.noreply.github.com>
Co-authored-by: mc <42146119+mchammer01@users.noreply.github.com>
Co-authored-by: skedwards88 <skedwards88@github.com>

content/actions/using-github-hosted-runners/about-github-hosted-runners.md

@@ -113,7 +113,7 @@ For the overall list of included tools for each runner operating system, see the
 
 * [Ubuntu 22.04 LTS](https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md)
 * [Ubuntu 20.04 LTS](https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2004-Readme.md)
-* [Ubuntu 18.04 LTS](https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu1804-Readme.md)
+* [Ubuntu 18.04 LTS](https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu1804-Readme.md) (deprecated)
 * [Windows Server 2022](https://github.com/actions/runner-images/blob/main/images/win/Windows2022-Readme.md)
 * [Windows Server 2019](https://github.com/actions/runner-images/blob/main/images/win/Windows2019-Readme.md)
 * [macOS 12](https://github.com/actions/runner-images/blob/main/images/macos/macos-12-Readme.md)

content/actions/using-workflows/workflow-syntax-for-github-actions.md

@@ -793,11 +793,11 @@ strategy:
   fail-fast: false
   matrix:
     node: [13, 14]
-    os: [macos-latest, ubuntu-18.04]
+    os: [macos-latest, ubuntu-latest]
     experimental: [false]
     include:
       - node: 15
-        os: ubuntu-18.04
+        os: ubuntu-latest
         experimental: true
 ```
 {% endraw %}

content/admin/github-actions/managing-access-to-actions-from-githubcom/setting-up-the-tool-cache-on-self-hosted-runners-without-internet-access.md

@@ -30,7 +30,7 @@ You can populate the runner tool cache by running a {% data variables.product.pr
 
 {% note %}
 
-**Note:** You can only use a {% data variables.product.prodname_dotcom %}-hosted runner's tool cache for a self-hosted runner that has an identical operating system and architecture. For example, if you are using a `ubuntu-18.04` {% data variables.product.prodname_dotcom %}-hosted runner to generate a tool cache, your self-hosted runner must be a 64-bit Ubuntu 18.04 machine. For more information on {% data variables.product.prodname_dotcom %}-hosted runners, see "[About {% data variables.product.prodname_dotcom %}-hosted runners](/free-pro-team@latest/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources)."
+**Note:** You can only use a {% data variables.product.prodname_dotcom %}-hosted runner's tool cache for a self-hosted runner that has an identical operating system and architecture. For example, if you are using a `ubuntu-22.04` {% data variables.product.prodname_dotcom %}-hosted runner to generate a tool cache, your self-hosted runner must be a 64-bit Ubuntu 22.04 machine. For more information on {% data variables.product.prodname_dotcom %}-hosted runners, see "[About {% data variables.product.prodname_dotcom %}-hosted runners](/free-pro-team@latest/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources)."
 
 {% endnote %}
 
@@ -45,14 +45,14 @@ You can populate the runner tool cache by running a {% data variables.product.pr
 1. On {% data variables.product.prodname_dotcom_the_website %}, navigate to a repository that you can use to run a {% data variables.product.prodname_actions %} workflow.
 1. Create a new workflow file in the repository's `.github/workflows` folder that uploads an artifact containing the {% data variables.product.prodname_dotcom %}-hosted runner's tool cache.
 
-   The following example demonstrates a workflow that uploads the tool cache for an Ubuntu 18.04 environment, using the `setup-node` action with Node.js versions 10 and 12.
+   The following example demonstrates a workflow that uploads the tool cache for an Ubuntu 22.04 environment, using the `setup-node` action with Node.js versions 10 and 12.
 
    ```yaml
    name: Upload Node.js 10 and 12 tool cache
    on: push
    jobs:
      upload_tool_cache:
-       runs-on: ubuntu-18.04
+       runs-on: ubuntu-22.04
        steps:
          - name: Clear any existing tool cache
            run: |

data/reusables/actions/jobs/multi-dimension-matrix.md

@@ -12,7 +12,7 @@ jobs:
   example_matrix:
     strategy:
       matrix:
-        os: [ubuntu-18.04, ubuntu-20.04]
+        os: [ubuntu-22.04, ubuntu-20.04]
         version: [10, 12, 14]
     runs-on: {% raw %}${{ matrix.os }}{% endraw %}
     steps:

data/reusables/actions/supported-github-runners.md

@@ -48,12 +48,13 @@ Ubuntu 20.04
 </tr>
 <tr>
 <td>
-Ubuntu 18.04
+Ubuntu 18.04 <sup>[deprecated]</sup>
 </td>
 <td>
 <code>ubuntu-18.04</code>
 </td>
 <td>
+Migrate to <code>ubuntu-20.04</code> or <code>ubuntu-22.04</code>. For more information, see <A href="https://github.blog/changelog/2022-08-09-github-actions-the-ubuntu-18-04-actions-runner-image-is-being-deprecated-and-will-be-removed-by-12-1-22/">this GitHub blog post</A>.
 </td>
 </tr>
 <tr>