docs/esp8266/tutorial: Fix comments of FrameBuffer examples.

The third and fourth parameters in display.rect() and display.fill_rect()
are not x,y coordinates, but are instead width,height values.  Update the
comment after the example to show the correct x,y coordinates of the bottom
right corner of each rectangle, respectively.

docs/esp8266/tutorial/ssd1306.rst

@@ -66,8 +66,8 @@ Subclassing FrameBuffer provides support for graphics primitives::
     display.hline(0, 8, 4, 1)               # draw horizontal line x=0, y=8, width=4, colour=1
     display.vline(0, 8, 4, 1)               # draw vertical line x=0, y=8, height=4, colour=1
     display.line(0, 0, 127, 63, 1)          # draw a line from 0,0 to 127,63
-    display.rect(10, 10, 107, 43, 1)        # draw a rectangle outline 10,10 to 107,43, colour=1
-    display.fill_rect(10, 10, 107, 43, 1)   # draw a solid rectangle 10,10 to 107,43, colour=1
+    display.rect(10, 10, 107, 43, 1)        # draw a rectangle outline 10,10 to 117,53, colour=1
+    display.fill_rect(10, 10, 107, 43, 1)   # draw a solid rectangle 10,10 to 117,53, colour=1
     display.text('Hello World', 0, 0, 1)    # draw some text at x=0, y=0, colour=1
     display.scroll(20, 0)                   # scroll 20 pixels to the right