styling and typo for Ecto models guide
styling and typo for Ecto models guide

Minor improvements to the Ecto models guide.
stevedomin/phoenix,0x00evil/phoenix,Kosmas/phoenix,evax/phoenix,mschae/phoenix,korobkov/phoenix,optikfluffel/phoenix,dmarkow/phoenix,eksperimental/phoenix,optikfluffel/phoenix,mobileoverlord/phoenix,mitchellhenke/phoenix,0x00evil/phoenix,phoenixframework/phoenix,pap/phoenix,bsmr-erlang/phoenix,jwarwick/phoenix,evax/phoenix,trarbr/phoenix,mobileoverlord/phoenix,keathley/phoenix,gjaldon/phoenix,michalmuskala/phoenix,Joe-noh/phoenix,jwarwick/phoenix,0x00evil/phoenix,rafbgarcia/phoenix,nshafer/phoenix,bsmr-erlang/phoenix,Gazler/phoenix,trarbr/phoenix,pap/phoenix,michalmuskala/phoenix,korobkov/phoenix,rafbgarcia/phoenix,mitchellhenke/phoenix,phoenixframework/phoenix,Joe-noh/phoenix,mschae/phoenix,phoenixframework/phoenix,nshafer/phoenix,gjaldon/phoenix,nshafer/phoenix,rafbgarcia/phoenix,optikfluffel/phoenix,stevedomin/phoenix,Kosmas/phoenix,keathley/phoenix,dmarkow/phoenix,Gazler/phoenix,eksperimental/phoenix