add comment regarding CloudMade key
add comment regarding CloudMade key

DT9/osmdroid,sibext/osmdroid-1,microg/android_external_osmdroid,prembasumatary/osmdroid,GeoODK/osmdroid,fpoyer/osmdroid,1nv4d3r5/osmdroid,osmdroid/osmdroid,osmdroid/osmdroid,osmdroid/osmdroid,dozd/osmdroid,1nv4d3r5/osmdroid,hyl1987419/osmdroid,beemogmbh/osmdroid,GeoODK/osmdroid,Sarfarazsajjad/osmdroid,ak-67/osmdroid,sibext/osmdroid-1,DShamaev/osmdroid,osmdroid/osmdroid,DT9/osmdroid,beemogmbh/osmdroid,fpoyer/osmdroid,hyl1987419/osmdroid,dozd/osmdroid,Sarfarazsajjad/osmdroid,DShamaev/osmdroid,microg/android_external_osmdroid,mozilla/osmdroid,ak-67/osmdroid,prembasumatary/osmdroid