Documentation for patch_all

[SamStephens]

There is no documentation of what patch_all actually does, even though it's included in an example in README.md.

This is particularly important due to #100, talking about the potential of surprises from patch_all

Does patch_all patch from a whitelist of known libraries that can be patched. Does it have some magic generic approach to try and patch all modules?

Looking at the code makes it clear patch_all patches from a whitelist, but it would be good for this to be documented.

Also, users of patch have to read code to understand what they can patch with it. Even a short piece of documentation linking into the code would lower the barrier of entry.

[SamStephens]

I see it's described here, but it'd be good if the API reference linked to that documentation page.

[carolabadeer]

Thanks for the feedback @SamStephens! The PR above adds clarification on the patch functions in the API documentation