Add reference projects as submodules

monmob (WiFi monitor mode), P4wnP1 (USB attack platform),
dustcloud-nexmon (Broadcom firmware patches), InternalBlue
(Bluetooth firmware patching). Docs updated with descriptions
and usage context for each.

.gitmodules

@@ -1,3 +1,15 @@
 [submodule "tools/rtl_tcp_andro"]
 	path = tools/rtl_tcp_andro
 	url = https://github.com/signalwareltd/rtl_tcp_andro-.git
+[submodule "tools/monmob"]
+	path = tools/monmob
+	url = https://github.com/tuter/monmob.git
+[submodule "tools/P4wnP1"]
+	path = tools/P4wnP1
+	url = https://github.com/RoganDawes/P4wnP1.git
+[submodule "tools/dustcloud-nexmon"]
+	path = tools/dustcloud-nexmon
+	url = https://github.com/dgiese/dustcloud-nexmon.git
+[submodule "tools/internalblue"]
+	path = tools/internalblue
+	url = https://github.com/seemoo-lab/internalblue.git