Add locale.maxTaskPar, adjust dataParTasksPerLocale.

Add documentation for the locale.maxTaskPar method, and document that
the default value of dataParTasksPerLocale is the .maxTaskPar for the
top-level locale.
Update the style of some cross-references.

Add "see ...", rather than leaving the cross-references bare.
Merge pull request #512 from gbtitus/spec-here.maxTaskPar

Add locale.maxTaskPar, adjust dataParTasksPerLocale.

Add documentation for the locale.maxTaskPar method, and document that
the default value of dataParTasksPerLocale is the .maxTaskPar for the
top-level locale.

Reviewed by Sung.