Describe templates in overview guide (#2588)
Describe templates in overview guide (#2588)

* An attemt a a description for templates

I'm not sure if this is the best description ever, but it is a bit more informative.

* Better copy for Template docs

this helps differentiate between a template and something like Plug.Static

Joe-noh/phoenix,korobkov/phoenix,keathley/phoenix,trarbr/phoenix,nshafer/phoenix,optikfluffel/phoenix,bsmr-erlang/phoenix,nshafer/phoenix,michalmuskala/phoenix,jwarwick/phoenix,mitchellhenke/phoenix,keathley/phoenix,eksperimental/phoenix,bsmr-erlang/phoenix,mschae/phoenix,Kosmas/phoenix,rafbgarcia/phoenix,dmarkow/phoenix,0x00evil/phoenix,evax/phoenix,mobileoverlord/phoenix,jwarwick/phoenix,trarbr/phoenix,eksperimental/phoenix,mitchellhenke/phoenix,mobileoverlord/phoenix,phoenixframework/phoenix,optikfluffel/phoenix,mschae/phoenix,Gazler/phoenix,michalmuskala/phoenix,pap/phoenix,Kosmas/phoenix,pap/phoenix,rafbgarcia/phoenix,dmarkow/phoenix,Joe-noh/phoenix,evax/phoenix,gjaldon/phoenix,optikfluffel/phoenix,rafbgarcia/phoenix,0x00evil/phoenix,nshafer/phoenix,stevedomin/phoenix,0x00evil/phoenix,korobkov/phoenix,phoenixframework/phoenix,phoenixframework/phoenix,gjaldon/phoenix,stevedomin/phoenix,Gazler/phoenix