[GHC] #15266: Add QuantifiedConstraints to release notes

[GHC]

#15266: Add QuantifiedConstraints to release notes
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 I was doing a pass through the release notes earlier today and added some
 language for `QuantifiedConstraints` but was interrupted. I'll try to
 commit tomorrow.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15266#comment:1>
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