Add feature state templates (#3680)

* Add feature state template

* tweak css

* change wording

* apply wording changes to alpha and beta

* tweak dialog css

* tweak code highlighting

* tweak dialog style

* set for_k8s_version default

* tweak dialog ul

* make init containers 1.5 beta for now

* set default dialog width

* revert a:visited color

* force code style

* simplify copy for alpha, beta, stable

* tweak code style

* fix beta dialog title

* fix dialog link a code

* remaining tweaks

* set a:visited color

* Address Steve's feedback

* rename dialog.md to feature-dialog.md

* remove bold from additional feature state text

_includes/feature-dialog.md

@@ -0,0 +1,28 @@
+<a href="#" id="feature-state-dialog-link" class="ui-state-default ui-corner-all"><span class="ui-icon ui-icon-newwin"></span>{{ dialog_title }}</a>
+<div id="feature-state-dialog" title="{{ dialog_title }}">
+{{ dialog_content | markdownify }}
+</div>
+{% raw %}<script>
+$(function(){
+    
+    $( "#feature-state-dialog" ).dialog({
+        autoOpen: false,
+        width: {% endraw %}{{ dialog_width | default: "600" }}{% raw %},
+        buttons: [
+            {
+                text: "Ok",
+                click: function() {
+                    $( this ).dialog( "close" );
+                }
+            }
+        ]
+    });
+
+    // Link to open the dialog
+    $( "#feature-state-dialog-link" ).click(function( event ) {
+        $( "#feature-state-dialog" ).dialog( "open" );
+        event.preventDefault();
+    });
+
+});
+</script>{% endraw %}