Update example code in sharding document
Update example code in sharding document

Don't rely on Sequel.connect not connecting immediately, as there
are cases where it will.  Use rand(num_servers) to get the starting
shard, so it doesn't always start with the first one.

reubano/sequel,beni55/sequel,pfarrell/sequel,gferguson-gd/sequel,pfarrell/sequel,yazshel/sequel,t-morgan/sequel,yazshel/sequel,reubano/sequel,uhoh-itsmaciek/sequel,t-morgan/sequel,seeARMS/sequel,knut2/sequel,mpalmer/sequel,nicohvi/sequel,nju520/sequel,davidbegin/sequel,nju520/sequel,seeARMS/sequel,beni55/sequel,nicohvi/sequel,uhoh-itsmaciek/sequel,knut2/sequel,gferguson-gd/sequel,davidbegin/sequel,mpalmer/sequel