added a note about building and running the echo example
added a note about building and running the echo example

hanw/connectal,cambridgehackers/connectal,cambridgehackers/connectal,csail-csg/connectal,hanw/connectal,chenm001/connectal,chenm001/connectal,hanw/connectal,cambridgehackers/connectal,8l/connectal,csail-csg/connectal,csail-csg/connectal,csail-csg/connectal,chenm001/connectal,8l/connectal,chenm001/connectal,8l/connectal,hanw/connectal,8l/connectal,cambridgehackers/connectal,hanw/connectal,cambridgehackers/connectal,csail-csg/connectal,chenm001/connectal,8l/connectal