Fix typo in ShallowWrapper and ReactWrapper docs: MyCStatefullass -> Stateful

[codecov[bot]]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (3a7701c) 96.42% compared to head (ad48340) 96.42%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2602 +/- ## ======================================= Coverage 96.42% 96.42% ======================================= Files 49 49 Lines 4332 4334 +2 Branches 1156 1156 ======================================= + Hits 4177 4179 +2 Misses 155 155 ``` [see 2 files with indirect coverage changes](https://app.codecov.io/gh/enzymejs/enzyme/pull/2602/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=enzymejs)

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[josephfrazier]

heh, I see it's in ReactWrapper too: https://github.com/enzymejs/enzyme/blob/3a7701ca24a02d55a07596676705c5cdc1a72472/docs/api/ReactWrapper/instance.md?plain=1#L41

Want me to fix that here, or in another PR, or will you take care of it?

[ljharb]

In the same PR, please :-) i'll get it if you don't, but please feel free to cover it in the meantime

[josephfrazier]

done!