Update ReadMe.md

Instructions how to build the fonts from source

ReadMe.md

@@ -8,6 +8,9 @@ Gidole is a minimal yet friendly version of the [DIN](https://en.wikipedia.org/w
 
 Thank me by donating to the [Ethiopian Red Cross Society](https://www.ammado.com/community/153173/donate) and/or show Gidole some social love and star it here on GitHub and share it on: [Twitter](https://twitter.com/intent/tweet?text=Gidole+-+Open+Source+Modern+DIN+by+@andreaslarsendk&url=https%3A%2F%2Fgidole.github.io), [Facebook](http://www.facebook.com/sharer/sharer.php?s=100&p%5Burl%5D=http%3A%2F%2Fgidole.github.io), [Google](https://plus.google.com/share?url=http://gidole.github.io), [LinkedIn](https://www.linkedin.com/shareArticle?mini=true&url=http://gidole.github.io) etc... :)
 
+Building from Source (fontforge is needed)
+`for a in *.sfdir; do fontforge -lang=ff -c 'Open($1); Generate($2)' $a $a.otf; done`
+
 ![Gidole](https://raw.githubusercontent.com/gidole/Gidole-Typefaces/master/Resources/GidoleScreenshots/1Gidole.png)
 ![GidoleC](https://raw.githubusercontent.com/gidole/Gidole-Typefaces/master/Resources/GidoleScreenshots/2GidoleCapital.png)
 ![GidoleL](https://raw.githubusercontent.com/gidole/Gidole-Typefaces/master/Resources/GidoleScreenshots/3GidoleLowercase.png)