Modify DeveloperGuide.adoc to use appendix styles and list continuation
Modify DeveloperGuide.adoc to use appendix styles and list continuation

damithc/addressbook-level4,damithc/addressbook-level4,CS2103R-Eugene-Peh/addressbook-level4,se-edu/addressbook-level3,CS2103R-Eugene-Peh/addressbook-level4,damithc/addressbook-level4,CS2103R-Eugene-Peh/addressbook-level4