Fix minor typos

dgl/NanoVG.hpp

@@ -192,10 +192,10 @@ private:
 
    @code
        const char* txt = "Text me up.";
-       textBounds(vg, x,y, txt, NULL, bounds);
-       beginPath(vg);
-       roundedRect(vg, bounds[0], bounds[1], bounds[2]-bounds[0], bounds[3]-bounds[1]);
-       fill(vg);
+       vg.textBounds(x,y, txt, NULL, bounds);
+       vg.beginPath();
+       vg.roundedRect(bounds[0], bounds[1], bounds[2]-bounds[0], bounds[3]-bounds[1]);
+       vg.fill();
    @endcode
 
    Note: currently only solid color fill is supported for text.

dgl/Widget.hpp

@@ -111,7 +111,7 @@ public:
    /**
       Mouse event.
       @a button The button number (1 = left, 2 = middle, 3 = right).
-      @a press  True if the key was pressed, false if released.
+      @a press  True if the button was pressed, false if released.
       @a pos    The widget-relative coordinates of the pointer.
       @see onMouse
     */