Steven clontz/codespace resources (#48)

* add codespace resources info

* fix image, tweak words

Author: StevenClontz

assets/screenshots/codespace-timeout-retention.png

@@ -284,6 +284,29 @@ A deleted Codespace can always be recreated later based upon your most
 recent commit.
       </p>
     </note>
+    <remark xml:id="remark-adjusting-defaults">
+      <p>
+<xref ref="figure-codespace-timeout-retention"/> shows a screenshot of
+some settings available on
+<url href="https://github.com/settings/codespaces">github.com/settings/codespaces</url>
+to adjust the default time your Codespace can idle before it times out
+(to save your compute time resources), and to adjust the default time
+your Codespace will be retained before it is deleted
+(to save your storage resources).
+      </p>
+    </remark>
+    <figure xml:id="figure-codespace-timeout-retention">
+      <caption>Screenshot of Codespace management settings</caption>
+      <image source="screenshots/codespace-timeout-retention.png">
+        <description>
+          <p>Screenshot of a web browser. Its text follows:</p>
+          <p>Default idle timeout</p>
+          <p>A codespace will suspend after a period of inactivity. You can specify a default idle timeout value, which will apply to all codespaces created after the default is changed. You will be charged for the entire time your codespace is running, even if it is idle. The maximum value is 240 minutes (4 hours).</p>
+          <p>Default retention period</p>
+          <p>Inactive codespaces are automatically deleted 30 days after the last time they were stopped. A shorter retention period can be set, and will apply to all codespaces created going forward. The default and maximum value is 30 days. Learn about retention setting</p>
+        </description>
+      </image>
+    </figure>
     <p>
 Putting it all together, we have seen three ways to access files on your repo.
 Going from the least easy to edit to the most editable we have: <c>GitHub.com</c>,