doc (analysis/normed_space/operator_norm): cleanup (#1906)
doc (analysis/normed_space/operator_norm): cleanup (#1906)

* doc (analysis/normed_space/operator_norm): cleanup

* typo

Co-authored-by: mergify[bot] <b09a6ee808b67e98a221404e7aaa52e0398a4954@users.noreply.github.com>

leanprover-community/mathlib,leanprover-community/mathlib