Link to .ini file description in configuration chapter.

The Startup chapter describes a Pyramid application's .ini file.
This is now a seealso in the Configuration chapter.
Link to logging configuration in the Startup chapter.

The Startup chapter describes the application's .ini file.  The
Logging chapter describes how to configure logging with the .ini file.
Add index entries for .ini files vis settings.
Merge pull request #1396 from kpinc/doc_config

Doc config