Update instructions after the removal of Scene3D

Signed-off-by: Jose Luis Rivero <jrivero@osrfoundation.org>

garden/sdf_worlds.md

@@ -80,28 +80,37 @@ Now let's define the GUI. Under the `<gui>` tag we specify anything related to t
 
 ```xml
 <!-- 3D scene -->
-<plugin filename="GzScene3D" name="3D View">
+<plugin filename="MinimalScene">
     <gz-gui>
-        <title>3D View</title>
-        <property type="bool" key="showTitleBar">false</property>
-        <property type="string" key="state">docked</property>
+      <title>3D View</title>
+      <property type="string" key="state">docked</property>
     </gz-gui>
-
     <engine>ogre2</engine>
     <scene>scene</scene>
-    <ambient_light>1.0 1.0 1.0</ambient_light>
+    <ambient_light>0.4 0.4 0.4</ambient_light>
     <background_color>0.8 0.8 0.8</background_color>
     <camera_pose>-6 0 6 0 0.5 0</camera_pose>
 </plugin>
 ```
 
-The `GzScene3D` plugin is responsible for displaying the 3D scene of our world. It has the following properties (most of the GUI plugins have them):
+The `MinimalScene` plugin is responsible for displaying the 3D scene of our world. It has the following properties (most of the GUI plugins have them):
 
-* `showTitleBar` if true it will show the blue title bar over the plugin with the name mentioned in the `<title>` tag.
 * `state` is the state of the plugin it can be docked in its place using `docked` or it can be `floating`.
 
 For the rendering engine we can choose `ogre` or `ogre2`. The `<ambient_light>` and the `<background_color>` specify the ambient and the background color of the scene. `<camera_pose>` specifies the `X Y Z` position of the camera followed by its rotation in `Roll Pitch Yaw`.
 
+#### Common used 3D scene controllers
+
+To provide some minimal functionality and controls, a part of the 3D scene implemented by `MinimalScene`,
+a [usual set of plugins](https://github.com/gazebosim/gz-sim/blob/ff1c82b41e548dfdc8076374f9500db2df2c35a1/examples/worlds/minimal_scene.sdf#L29-L128) can be copied from the `gz-sim` repository.
+
+These plugins have the following properties (most of the GUI plugins have them):
+
+* `resizable`: if true the user can change plugin size in the interface
+* `height` and `width`: size measures of the plugin
+* `state` is the state of the plugin it can be docked in its place using `docked` or it can be `floating`.
+* `showTitleBar` if true it will show the blue title bar over the plugin with the name mentioned in the `<title>` tag.
+
 ### World control plugin
 
 ```xml