documentation/interface for KSPDefaultConverged

[Boyce Griffith]

Hi, Folks --

It appears that the documentation for KSPDefaultConverged may need to be 
updated to indicate that the convergence context used by 
KSPDefaultConverged is NOT unused and must be created 
byKSPDefaultConvergedCreate.

Also, since the context is not an unused dummy variable, perhaps it 
might be clearer if its name was changed to `ctx' from `dummy' in the 
definition of KSPDefaultConverged?

Thanks!

-- Boyce