feat: add accTitle/accDescr to class diagram in WebGL architecture doc

Author: coseeian

contributor_docs/webgl_mode_architecture.md

@@ -249,6 +249,11 @@ It also has the following per-vertex attributes:
 title: p5.js WebGL Classes
 ---
 classDiagram
+    accTitle: p5.js WebGL Class Diagram
+    accDescr {
+      "p5.Renderer" is the base class for "p5.Renderer2D" and "p5.RendererGL".
+      "p5.RendererGL" has a one-to-many composition relationship with multiple "p5.Shaders", "p5.Textures", and "p5.Framebuffers". Additionally, "p5.RendererGL" has a many-to-many aggregation relationship with "p5.Geometry".
+    }
     class Base["p5.Renderer"] {
     }
     class P2D["p5.Renderer2D"] {