update visualize development docs (#20507)

docs/development/visualize/development-embedding-visualizations.asciidoc

@@ -1,11 +1,7 @@
 [[development-embedding-visualizations]]
 === Embedding Visualizations
 
-There are two different methods you can use to insert a visualization in your page.
+To embed visualization use the `VisualizeLoader`.
-
-To display an already saved visualization, use the `VisualizeLoader`.
-To reuse an existing visualization implementation for a more custom purpose,
-use the Angular `<visualization>` directive instead.
 
 ==== VisualizeLoader
 
@@ -59,46 +55,3 @@ The returned `EmbeddedVisualizeHandler` itself has the following methods and pro
 
 You can find the detailed `EmbeddedVisualizeHandler` documentation in its
 {repo}blob/{branch}/src/ui/public/visualize/loader/embedded_visualize_handler.js[source code].
-
-We recommend *not* to use the internal `<visualize>` Angular directive directly.
-
-==== `<visualization>` directive
-The `<visualization>` directive takes a visualization configuration and data.
-It should be used, if you don't want to render a saved visualization, but specify
-the config and data directly.
-
-`<visualization vis='vis' vis-data='visData' ui-state='uiState' ></visualization>` where
-
-`vis` is an instance of `Vis` object. The constructor takes 3 parameters:
-
-- `indexPattern` <string>: the indexPattern you want to pass to the visualization
-- `visConfig` <object>: the configuration object
-- `uiState` <object>: uiState object you want to pass to Vis. If not provided Vis will create its own.
-
-`visData` is the data object. Each visualization defines a `responseHandler`, which defines the format of this object.
-
-`uiState` is an instance of PersistedState. Visualizations use it to keep track of their current state. If not provided
-`<visualization>` will create its own (but you won't be able to check its values)
-
-*code example: create single metric visualization*
-["source","html"]
------------
-<div ng-controller="KbnTestController" class="test_vis">
-  <visualization vis='vis' vis-data='visData'></visualize>
-</div>
------------
-["source","js"]
------------
-import { uiModules } from 'ui/modules';
-
-uiModules.get('kibana')
-.controller('KbnTestController', function ($scope) {
-  const visConfig = {
-    type: 'metric'
-  };
-  $scope.vis = new Vis('.logstash*', visConfig);
-  $scope.visData = [{ columns: [{ title: 'Count' }], rows: [[ 1024 ], [ 256 ]] }];
-});
------------
-
-<visualization> will trigger `renderComplete` event on the element once it's done rendering.