Added xbm preview image

Author: squix78

README.md

@@ -32,6 +32,7 @@ Fonts are defined in a proprietary but open format. You can create new font file
 of open sourced Fonts from this web app: http://oleddisplay.squix.ch
 Choose the font family, style and size, check the preview image and if you like what you see click the "Create" button. This will create the font array in a text area form where you can copy and paste it into a new or existing header file.
 
+
 ![FontTool](https://github.com/squix78/esp8266-oled-ssd1306/raw/master/resources/FontTool.png)