Add some initial information on how to install raylib on FreeBSD

Working-on-FreeBSD.md

@@ -0,0 +1,13 @@
+# Installation
+
+raylib can be installed on FreeBSD with pkg (prebuiled binary package, recommended):
+
+```console
+# pkg install raylib
+```
+
+or using the FreeBSD Ports Collection (building from source, if you want to modify the sources):
+
+```console
+# cd /usr/ports/devel/raylib && make install clean
+```