Fix typo: 'generated' -> 'generate'

Minor typo fix: "used to generated" -> "used to generate"

Author: theDrake

tutorials/3d/procedural_geometry/index.rst

@@ -115,7 +115,7 @@ ImmediateMesh
 ImmediateMesh is a mesh that uses an immediate mode style interface (like
 SurfaceTool) to draw objects. The difference between ImmediateMesh and the
 SurfaceTool is that ImmediateMesh is drawn directly with code dynamically, while
-the SurfaceTool is used to generated a Mesh that you can do whatever you want
+the SurfaceTool is used to generate a Mesh that you can do whatever you want
 with.
 
 ImmediateMesh is useful for prototyping because of its straightforward API, but