wpa_supplicant: add page (#2290)

pages/common/wpa_supplicant.md

@@ -0,0 +1,11 @@
+# wpa_supplicant
+
+> Manage protected wireless networks.
+
+- Join a protected wireless network:
+
+`wpa_supplicant -i {{interface}} -c {{path/to/wpa_supplicant_conf.conf}}`
+
+- Join a protected wireless network and run it in a daemon:
+
+`wpa_supplicant -B -i {{interface}} -c {{path/to/wpa_supplicant_conf.conf}}`