[GHC] #11015: Add note describing unit ids, unit keys, package ids, and package keys,

[GHC]

#11015: Add note describing unit ids, unit keys, package ids, and package keys,
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        Reporter:  bgamari           |                Owner:  ezyang
            Type:  task              |               Status:  patch
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1776
       Wiki Page:                    |
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Comment (by Edward Z. Yang <ezyang@…>):

 In [changeset:"91f1c600614e8c456a62bd95611400b442113cdf/ghc" 91f1c60/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="91f1c600614e8c456a62bd95611400b442113cdf"
 Fix #11015 with a nice note.

 Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>

 Test Plan: doc only

 Reviewers: bgamari, austin

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1776

 GHC Trac Issues: #11015
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11015#comment:7>
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