chore(category_theory/closed/monoidal): fix notation (#12612)
chore(category_theory/closed/monoidal): fix notation (#12612)

Previously the `C` in the internal hom arrow ` ⟶[C] ` was hardcoded, which wasn't very useful!

I've also reduced the precedence slightly, so we now require more parentheses, but I think these are less confusing rather than more so it is a good side effect?



Co-authored-by: Scott Morrison <63f04b4d96235eb042cc46d94f14d241d2a26722@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib