Add submodule USB_Host_Shield_2.0 from my repositry.

.gitmodules

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+[submodule "protocol/usb_hid/USB_Host_Shield_2.0"]
+	path = protocol/usb_hid/USB_Host_Shield_2.0
+	url = git@github.com:tmk/USB_Host_Shield_2.0.git

protocol/usb_hid/USB_Host_Shield_2.0

@@ -0,0 +1 @@
+Subproject commit 8bb790f83af298b5f3e5516259c9d8ec27efe522