Add HOWTO define new config option doc
Add HOWTO define new config option doc

Summary:
Document how to define new command line and config file options, and
slight cleanup.

Reviewed By: jvillard

Differential Revision: D3528952

fbshipit-source-id: 6bd7601

facebook/infer,ryoon/infer,facebook/infer,facebook/infer,blzq/infer,jsachs/infer,ropas/infer,jvillard/infer,xennygrimmato/infer,kageiit/infer,jvillard/infer,xennygrimmato/infer,ryoon/infer,xennygrimmato/infer,ropas/infer,kageiit/infer,jsachs/infer,ropas/infer,xennygrimmato/infer,facebook/infer,blzq/infer,facebook/infer,kageiit/infer,ryoon/infer,kageiit/infer,ropas/infer,facebook/infer,kageiit/infer,jvillard/infer,ryoon/infer,xennygrimmato/infer,ropas/infer,xennygrimmato/infer,jsachs/infer,jvillard/infer,ropas/infer,jvillard/infer,jsachs/infer,blzq/infer,facebook/infer,jvillard/infer,blzq/infer,blzq/infer,xennygrimmato/infer,blzq/infer,kageiit/infer,kageiit/infer,jsachs/infer,ryoon/infer,jvillard/infer,jsachs/infer,ryoon/infer