Fix usages in README and doc comment

[Trundle]

What's in this pull request?

Fixes a usage shown in README: Bool.suchThat is mentioned, but it doesn't exist.

Why merge this pull request?

It makes the documentation a bit more c/p friendly.

What's worth discussing about this pull request?

:man_shrugging:

What downsides are there to merging this pull request?

:man_shrugging: