Added an introductory paragraph to the subdomains addition to the domains primer
Added an introductory paragraph to the subdomains addition to the domains primer

To introduce the concept and help it flow from the rest of the primer
a bit better.



git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@19293 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

sungeunchoi/chapel,hildeth/chapel,CoryMcCartan/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,chizarlicious/chapel,chizarlicious/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,chizarlicious/chapel,sungeunchoi/chapel,sungeunchoi/chapel,chizarlicious/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,hildeth/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,chizarlicious/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,sungeunchoi/chapel,hildeth/chapel