Add banner for templating to devel docs (#2627)

* add banner to note the template changes

* get rid of extra whitespace

* Update docs/docsite/.templates/banner.html

Co-authored-by: Don Naro <[email protected]>

* add version

* implement feedback

* remove duplicate test banner

* one more extra line

* change wording

* Update docs/docsite/.templates/banner.html

---------

Co-authored-by: Don Naro <[email protected]>

Author: samccann

docs/docsite/.templates/banner.html

@@ -50,6 +50,8 @@
         banner += extra_banner;
 
         msg += 'You are reading the <b>devel</b> version of the Ansible documentation - this version is not guaranteed stable. Use the version selection to the left if you want the <b>latest</b> (stable) released version.';
+        /* temp - add extra warning about core-2.19. This should move to latest at release time */
+        msg += '<br><p><strong>Important:</strong> The ansible-core 2.19/Ansible 12 release has made <b>significant templating changes that might require you to update playbooks and roles</b>. The templating changes enable reporting of numerous problematic behaviors that went undetected in previous releases, with wide-ranging positive effects on security, performance, and user experience. You should validate your content to ensure compatibility with these templating changes before upgrading to ansible-core 2.19 or Ansible 12. See the <a href="https://docs.ansible.com/ansible/devel/porting_guides/porting_guide_12.html">porting guide</a> to understand where you may need to update your playbooks and roles.';
       } else {
         msg += 'You are reading an older version of the Ansible documentation. Use the version selection to the left if you want the <b>latest</b> (stable) released version.';
         /* temp extra banner to advertise something - this is for testing*/