minor: documentation comment for constrintern.ml:sort_fields
minor: documentation comment for constrintern.ml:sort_fields

(Because the function is private to the module, it is documented in
the .ml rather than the .mli)

amintimany/coq,gares/coq,ppedrot/coq,coq/coq,JasonGross/coq,Ptival/coq,ejgallego/coq,SkySkimmer/coq,letouzey/coq-wip,william-lawvere/coq,amintimany/coq,Matafou/coq,gares/coq,gares/coq,coq/coq,silene/coq,Zimmi48/coq,letouzey/coq-wip,SkySkimmer/coq,ejgallego/coq,letouzey/coq-wip,Zimmi48/coq,maximedenes/coq,JasonGross/coq,gares/coq,letouzey/coq-wip,JasonGross/coq,Zimmi48/coq,maximedenes/coq,william-lawvere/coq,amintimany/coq,silene/coq,maximedenes/coq,ppedrot/coq,ejgallego/coq,SkySkimmer/coq,JasonGross/coq,maximedenes/coq,coq/coq,william-lawvere/coq,Matafou/coq,maximedenes/coq,Lionel-Rieg/coq,Lionel-Rieg/coq,coq/coq,Lionel-Rieg/coq,Ptival/coq,ppedrot/coq,ppedrot/coq,Zimmi48/coq,gares/coq,Ptival/coq,ejgallego/coq,letouzey/coq-wip,ppedrot/coq,SkySkimmer/coq,silene/coq,Matafou/coq