added missing include and missing semicolon to readme

Author: amock

README.md

@@ -19,14 +19,15 @@ C++:
 
 ``` C++
 #include "polyscope/polyscope.h"
+#include "polyscope/point_cloud.h"
 #include "polyscope/surface_mesh.h"
 
 // Initialize polyscope
 polyscope::init();
 
 // Register a point cloud
 // `points` is a Nx3 array-like container of points
-polyscope::registerPointCloud("my points", points)
+polyscope::registerPointCloud("my points", points);
 
 // Register a surface mesh structure
 // `meshVerts` is a Vx3 array-like container of vertex positions