[MacPorts] #62143: Document master_site_local, patch_site_local, archive_site_local in guide

[MacPorts]

#62143: Document master_site_local, patch_site_local, archive_site_local in guide
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  Reporter:  snowflake    |      Owner:  (none)
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  guide        |    Version:
Resolution:               |   Keywords:
      Port:               |
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Comment (by snowflake):

 I've tried setting master_site_local and patch_site_local and they do not
 work. I tried them as upper-case environment variables and that does not
 work. I've put debugging ui_notice's in the Tcl to print out the list of
 sites at various places in the code and get nothing.

 archive_site_local does work. Putting the sites in the file
 _resources/port1.0/fetch/mirror_sites.tcl works.

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Ticket URL: <https://trac.macports.org/ticket/62143#comment:3>
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