Docs: Clarify usage of ImmediateRenderObject.

docs/api/en/extras/objects/ImmediateRenderObject.html

@@ -13,11 +13,11 @@
 		<h1>[name]</h1>
 
 		<p class="desc">
-			This experimental class provides a fast code path for rendering meshes. When the renderer
-			encounters an instance of [name], it only takes care about the most primitive rendering
-			operations (e.g. binding vertex attributes, determining correct shader program or perfoming the
-			actual draw call). Features like view frustum culling, wireframe rendering or using multiple
-			materials are not supported. Besides [name] can only be used to render triangles.
+			This experimental class provides a fast code path for rendering meshes with frequently updated
+			geometry data. When the renderer encounters an instance of [name], it only takes care about
+			the most primitive rendering operations (e.g. binding vertex attributes, determining correct shader
+			program or perfoming the actual draw call). Features like view frustum culling, wireframe rendering
+			or using multiple materials are not supported. Besides [name] can only be used to render triangles.
 		</p>
 
 		<p class="desc">
@@ -25,6 +25,11 @@
 			raw geometry data have to be maintained as properties of the [name].
 		</p>
 
+		<p class="desc">
+			Using [name] makes only sense if you are updating your geometry data per frame. You can then
+			benefit of a faster code path compared to the default mesh redering logic.
+		</p>
+
 		<h2>Examples</h2>
 		<p>
 			[example:webgl_marchingcubes Marching Cubes]

docs/api/zh/extras/objects/ImmediateRenderObject.html

@@ -13,11 +13,11 @@
 		<h1>即时渲染对象([name])</h1>
 
 		<p class="desc">
-			This experimental class provides a fast code path for rendering meshes. When the renderer
-			encounters an instance of [name], it only takes care about the most primitive rendering
-			operations (e.g. binding vertex attributes, determining correct shader program or perfoming the
-			actual draw call). Features like view frustum culling, wireframe rendering or using multiple
-			materials are not supported. Besides [name] can only be used to render triangles.
+			This experimental class provides a fast code path for rendering meshes with frequently updated
+			geometry data. When the renderer encounters an instance of [name], it only takes care about
+			the most primitive rendering operations (e.g. binding vertex attributes, determining correct shader
+			program or perfoming the actual draw call). Features like view frustum culling, wireframe rendering
+			or using multiple materials are not supported. Besides [name] can only be used to render triangles.
 		</p>
 
 		<p class="desc">
@@ -25,6 +25,11 @@
 			raw geometry data have to be maintained as properties of the [name].
 		</p>
 
+		<p class="desc">
+			Using [name] makes only sense if you are updating your geometry data per frame. You can then
+			benefit of a faster code path compared to the default mesh redering logic.
+		</p>
+
 		<h2>例子</h2>
 		<p>
 			[example:webgl_marchingcubes Marching Cubes]