Update submodule path

- Migrate to openbeagle.org from old git.beagleboard.org

Signed-off-by: Ayush Singh <ayush@beagleboard.org>

.gitmodules

 [submodule "books/beaglebone-cookbook/code"]
 	path = books/beaglebone-cookbook/code
-	url = https://git.beagleboard.org/beagleboard/beaglebone-cookbook-code.git
+	url = https://openbeagle.org/beagleboard/beaglebone-cookbook-code.git
 [submodule "books/pru-cookbook/code"]
 	path = books/pru-cookbook/code
-	url = https://git.beagleboard.org/beagleboard/pru-cookbook-code
+	url = https://openbeagle.org/beagleboard/pru-cookbook-code
 [submodule "projects/librobotcontrol"]
 	path = projects/librobotcontrol
-	url = https://git.beagleboard.org/beagleboard/librobotcontrol
+	url = https://openbeagle.org/beagleboard/librobotcontrol