Small info block in the beginning of the automated publishing section. (#8352)

Author: isoos

app/lib/frontend/templates/views/pkg/admin_page.dart

@@ -271,6 +271,11 @@ d.Node _automatedPublishing(Package package) {
   return d.fragment([
     d.a(name: 'automated-publishing'),
     d.h2(text: 'Automated publishing'),
+    d.markdown(
+        'You can automate publishing from the supported automated deployment environments. '
+        'Instead of creating long-lived secrets, you may use temporary OpenID-Connect tokens '
+        'signed by either GitHub Actions or Google Cloud IAM. '
+        'See the [pub automated publishing guide](https://dart.dev/tools/pub/automated-publishing) for further details.'),
     d.a(name: 'github-actions'),
     d.h3(text: 'Publishing from GitHub Actions'),
     d.div(

app/test/frontend/golden/pkg_admin_page.html

@@ -403,6 +403,11 @@ <h3>Unlisted</h3>
                   </div>
                   <a name="automated-publishing"></a>
                   <h2>Automated publishing</h2>
+                  <p>
+                    You can automate publishing from the supported automated deployment environments. Instead of creating long-lived secrets, you may use temporary OpenID-Connect tokens signed by either GitHub Actions or Google Cloud IAM. See the
+                    <a href="https://dart.dev/tools/pub/automated-publishing">pub automated publishing guide</a>
+                    for further details.
+                  </p>
                   <a name="github-actions"></a>
                   <h3>Publishing from GitHub Actions</h3>
                   <div class="-pub-form-checkbox-row -pub-form-checkbox-toggle-next-sibling">