Update readme.md

examples/TFTShape/readme.md

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 TFTShape is an extension  to draw shape-based objects on screen. The target of this extension is to abstract low level primitives but with full use of the TFT_eSPI core functions (no setPixel operations). Shapes are graphical objects with the most common 2D functionality such as draw, fill, scale and rotate. Shapes consists of vertices which will be interpteted by the TFTShape class to form points, lines, polygons etc. Vertices can be user defined or they can be generated by various TFTShape  builder functions. To give you an overview, here is a short example to see how to use this extension:
 ##Building an analog clock
 ### clock-face
+To draw a clock face, only three lines of code will be needed. The basic idea is to define a 12-sided grid and draw a small dot on the corners of the grid. Fortunately TFTShape has the functionality not only to draw the shape itself but it can take also an argument to draw another shape (at all vertices positions). So the code is very simple: create a shape used for the 5 minutes dots, create a shape for an invisible grid and finally draw this grid with a Shape as an argument:
+```javascript
+  TFTShape dot=TFTShape::buildNgon(8,6);
+  TFTShape grid5minutes=TFTShape::buildNgon(12,100);
+  grid5minutes.fill(&tft2,120,160,dot,TFT_GREY);
 
+```
+And this is the result:
 ![clock-face](images/screenshot_4571.png)