Copy binder types from actual declaration, fixes display of or.inl

[alexjbest]

Currently doc-gen prints or.inl as

inductive or (a b : Prop) :
Prop
inl : ∀ (a b : Prop), a → a ∨ b
inr : ∀ (a b : Prop), b → a ∨ b

but #check or.inl gives or.inl : ∀ {a b : Prop}, a → a ∨ b with implicit a b.
To fix this we copy the binder types from the actual declaration to the local constants used to pretty print the type

[alexjbest]

#deploy
I guess cargo-culting github commands won't work for me :D

[gebner]

#deploy

[github-actions]

This PR has been successfully deployed at http://leanprover-community.github.io/mathlib_docs_demo!

[alexjbest]

Ok, https://leanprover-community.github.io/mathlib_docs_demo/init/core.html#or looks better now, I checked a few other inductives and they seem fine too.