update readme for starting on boot

README.md

@@ -30,6 +30,11 @@ Just *./run.sh*.
 
 # Including this in B2G
 
-Just clone this repo inside $B2G/system/. Build and flash B2G as usual
+Just clone this repo inside *$B2G_REPO/system/*. Build and flash B2G as usual
 and then you will be able to run the agent using `sutagent`. It will be
 in the $PATH.
+
+# Start the agent on boot
+
+Add a `sutagent &` line after the exports in
+*$B2G_REPO/gonk-misc/b2g.sh*.