Update API Reference

API-Reference.md

@@ -7,6 +7,10 @@ The following functions are provided by the library:
 |s.cls(color=0)|Clear screen|
 |s.rectfill(x, y, w, h, color=0)|Filled rectangle|
 |s.circfill(x, y, r, color=0)|Filled circle|
+|s.ovalfill(x, y, rx, ry, color = 0)|Filled oval|
+|s.rect(x, y, w, h, color=0)|Rectangle|
+|s.circ(x, y, r, color=0)|Circle|
+|s.oval(x, y, rx, ry, color = 0)|Oval|
 |s.line(x1, y1, x2, y2, color=0)|Line segment|
 |s.text(x, y, message, color=3, size="normal")|Text rendering|