chore(data/real/basic): tweak lemmas about `of_cauchy` (#12829)
chore(data/real/basic): tweak lemmas about `of_cauchy` (#12829)

These lemmas are about `real.of_cauchy` not `real.cauchy`, as their name suggests.
This also flips the direction of some of the lemmas to be consistent with the zero and one lemmas.
Finally, this adds the lemmas about `real.cauchy` that are missing.







leanprover-community/mathlib,leanprover-community/mathlib