Document mkWeak#
Document mkWeak#

Reviewers: simonmar, austin

Reviewed By: simonmar

Subscribers: RyanGlScott, rwbarton, thomie

GHC Trac Issues: #10640, #13611

Differential Revision: https://phabricator.haskell.org/D3498

ezyang/ghc,shlevy/ghc,sdiehl/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc,sdiehl/ghc,sdiehl/ghc,shlevy/ghc,ezyang/ghc,sdiehl/ghc,ezyang/ghc,shlevy/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,ezyang/ghc,ezyang/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc