text: Title: add doc section to autogenerate talking about include_object use cases
  Body: **Migrated issue, originally created by Michael Bayer ([@zzzeek](https://github.com/zzzeek))**
  
  e.g. to http://alembic.readthedocs.org/en/latest/autogenerate.html including:
  
  1. using Tables for views
  
  2. working around constraint names that are truncated
  
  add a link from the current include_object docstring (which isn't in sphinx search since it's paramref)
  
  