Remove description of structure of opaque type `gb_trees:tree/2`.
Remove description of structure of opaque type `gb_trees:tree/2`.

Since it's an opaque type, its internal structure shouldn't be
part of the docs. Otherwise it leads misguided devs to the
assumption that they can pattern-match on it, when they shouldn't.

bjorng/otp,rlipscombe/otp,bjorng/otp,isvilen/otp,bjorng/otp,potatosalad/otp,g-andrade/otp,electricimp/otp,lrascao/otp,potatosalad/otp,jj1bdx/otp,electricimp/otp,uabboli/otp,bjorng/otp,legoscia/otp,getong/otp,dgud/otp,uabboli/otp,mikpe/otp,ferd/otp,emacsmirror/erlang,rlipscombe/otp,kvakvs/otp,legoscia/otp,emacsmirror/erlang,mikpe/otp,dumbbell/otp,isvilen/otp,bsmr-erlang/otp,electricimp/otp,aboroska/otp,vladdu/otp,g-andrade/otp,kvakvs/otp,jj1bdx/otp,legoscia/otp,erlang/otp,dgud/otp,legoscia/otp,erlang/otp,isvilen/otp,uabboli/otp,vinoski/otp,isvilen/otp,getong/otp,erlang/otp,isvilen/otp,potatosalad/otp,rlipscombe/otp,aboroska/otp,erlang/otp,vladdu/otp,lrascao/otp,uabboli/otp,bjorng/otp,getong/otp,electricimp/otp,aboroska/otp,dgud/otp,isvilen/otp,erlang/otp,legoscia/otp,aboroska/otp,vinoski/otp,vladdu/otp,electricimp/otp,vladdu/otp,rlipscombe/otp,dumbbell/otp,erlang/otp,mikpe/otp,emacsmirror/erlang,vinoski/otp,aboroska/otp,vinoski/otp,dumbbell/otp,uabboli/otp,vladdu/otp,lrascao/otp,getong/otp,RoadRunnr/otp,emacsmirror/erlang,dumbbell/otp,lrascao/otp,legoscia/otp,erlang/otp,erlang/otp,RoadRunnr/otp,erlang/otp,legoscia/otp,g-andrade/otp,jj1bdx/otp,dumbbell/otp,RoadRunnr/otp,mikpe/otp,lrascao/otp,vinoski/otp,kvakvs/otp,RoadRunnr/otp,vinoski/otp,jj1bdx/otp,legoscia/otp,RoadRunnr/otp,ferd/otp,jj1bdx/otp,jj1bdx/otp,bsmr-erlang/otp,potatosalad/otp,bjorng/otp,kvakvs/otp,RoadRunnr/otp,dgud/otp,jj1bdx/otp,bsmr-erlang/otp,vinoski/otp,isvilen/otp,vinoski/otp,dumbbell/otp,uabboli/otp,ferd/otp,bsmr-erlang/otp,g-andrade/otp,getong/otp,dgud/otp,uabboli/otp,bjorng/otp,ferd/otp,legoscia/otp,mikpe/otp,rlipscombe/otp,mikpe/otp,g-andrade/otp,emacsmirror/erlang,vladdu/otp,mikpe/otp,aboroska/otp,vinoski/otp,emacsmirror/erlang,lrascao/otp,rlipscombe/otp,dgud/otp,bjorng/otp,dgud/otp,g-andrade/otp,RoadRunnr/otp,ferd/otp,vladdu/otp,dgud/otp,dumbbell/otp,getong/otp,potatosalad/otp,isvilen/otp,bsmr-erlang/otp,ferd/otp,jj1bdx/otp,kvakvs/otp,uabboli/otp,rlipscombe/otp,aboroska/otp,mikpe/otp,isvilen/otp,potatosalad/otp,bjorng/otp,lrascao/otp,dumbbell/otp,getong/otp,potatosalad/otp,kvakvs/otp,bsmr-erlang/otp,RoadRunnr/otp,bsmr-erlang/otp,emacsmirror/erlang,jj1bdx/otp,getong/otp,uabboli/otp,aboroska/otp,kvakvs/otp,rlipscombe/otp,electricimp/otp,dgud/otp,jj1bdx/otp,getong/otp,bsmr-erlang/otp,g-andrade/otp,potatosalad/otp,electricimp/otp,dgud/otp,vladdu/otp,g-andrade/otp,emacsmirror/erlang,ferd/otp,rlipscombe/otp,electricimp/otp,kvakvs/otp,g-andrade/otp,potatosalad/otp,dumbbell/otp,bsmr-erlang/otp,lrascao/otp,isvilen/otp,kvakvs/otp,emacsmirror/erlang,mikpe/otp,lrascao/otp,potatosalad/otp,RoadRunnr/otp,dumbbell/otp,aboroska/otp,electricimp/otp,vladdu/otp,getong/otp,mikpe/otp,bjorng/otp,vinoski/otp,emacsmirror/erlang,ferd/otp,ferd/otp,erlang/otp,rlipscombe/otp,g-andrade/otp