Check/Document mapping of FluentAssertions to Testably.Expectations

[vbreuss]

Check all methods in FluentAssertions and document the corresponding expectation in Testably.Expectations.

See e.g. the following table:

Group	fluentassertions	Testably.Expectations
Boolean	.Should().BeFalse()	.Should().BeFalse()
	.Should().BeTrue()	.Should().BeTrue()
	.Should().Be(bool)	.Should().Be(bool)
	.Should().NotBe(bool)	.Should().NotBe(bool)
	.Should().Imply(bool)	.Should().Imply(bool)