add dev branch checkout to readme
add dev branch checkout to readme

JHeimbach/Dime,phpugl/Dime,phpugl/Dime,dime-timetracker/server-symfony,phpugl/Dime,JHeimbach/Dime,dime-timetracker/server-symfony,JHeimbach/Dime,JHeimbach/Dime,phpugl/Dime,dime-timetracker/server-symfony