Update README.localeModels
Update README.localeModels

[reviewed by Sungeun]

* Remove need to explicitly set CHPL_TASKS=qthreads
* Remove need to download, build, and install hwloc.  The hwloc library is
  included now and builds automatically for the numa locale model.
* Added a pointer to README.tasks for more information on qthreads and tuning
  qthreads parameters.
* Change caveat about not mapping iteration over distributed arrays to NUMA
  domains to not include Block. (r22726)


git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@23112 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

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