Add a banner message to warn when not on latest documentation (#58526)

* add banner to versions that are not latest

* move div into script

* fix div

* move comment

* fix shippable errors

docs/docsite/_themes/sphinx_rtd_theme/ansible_banner.html

@@ -0,0 +1,24 @@
+<!--- Based on sphinx versionwarning extension. Extension currently only works on READTHEDOCS -->
+{# Creates a banner at the top of the page for any version not latest. #}
+  <script>
+    current_url = window.location.href;
+    if ((current_url.search("latest") > -1) || (current_url.search("/{{ latest_version }}/") > -1)) {
+     // no banner for latest release
+    } else if (current_url.search("devel") > -1) {
+      document.write('<div id="banner_id" class="admonition caution">');
+      para = document.createElement('p');
+      banner_text=document.createTextNode("You are reading the *devel* version of the Ansible documentation - this version is not guaranteed stable. Use the version selection to the left if you want the latest stable released version.");
+      para.appendChild(banner_text);
+      element = document.getElementById('banner_id');
+      element.appendChild(para);
+      document.write('</div>');
+    } else {
+      document.write('<div id="banner_id" class="admonition caution">');
+      para = document.createElement('p');
+      banner_text=document.createTextNode("You are reading an older version of the Ansible documentation. Use the version selection to the left if you want the latest stable released version.");
+      para.appendChild(banner_text);
+      element = document.getElementById('banner_id');
+      element.appendChild(para);
+      document.write('</div>');
+    }
+  </script>

docs/docsite/_themes/sphinx_rtd_theme/layout.html

@@ -232,6 +232,8 @@
         </div> -->
 
           {% include "breadcrumbs.html" %}
+          
+          {% include "ansible_banner.html" %}
           <div id="page-content">
           {% block body %}{% endblock %}
           </div>

docs/docsite/rst/conf.py

@@ -144,7 +144,11 @@ html_context = {
     'github_user': 'ansible',
     'github_repo': 'ansible',
     'github_version': 'devel/docs/docsite/rst/',
-    'github_module_version': 'devel/lib/ansible/modules/'
+    'github_module_version': 'devel/lib/ansible/modules/',
+    'current_version': version,
+    'latest_version': '2.8',
+    # list specifically out of order to make latest work
+    'available_versions': ('latest', '2.7', '2.6', 'devel')
 }
 
 # The style sheet to use for HTML and HTML Help pages. A file of that name
@@ -263,9 +267,3 @@ autoclass_content = 'both'
 intersphinx_mapping = {'python': ('https://docs.python.org/2/', (None, '../python2-2.7.13.inv')),
                        'python3': ('https://docs.python.org/3/', (None, '../python3-3.6.2.inv')),
                        'jinja2': ('http://jinja.pocoo.org/docs/', (None, '../jinja2-2.9.7.inv'))}
-
-# list specifically out of order to make latest work
-html_context = {
-    'current_version': version,
-    'available_versions': ('latest', '2.7', '2.6', 'devel')
-}