[tenstad]

Description of your changes

Documents #119 (specifically tenstad#1)

The fix recomputes the requirements against the merged environment before
returning. Requirements that grew are how a Function asks to be called again, so
Crossplane fetches the newly selected EnvironmentConfigs and calls us once more;
they stabilise as soon as a pass selects nothing new.

Two limits worth knowing, both of which I think are fine to document rather than
solve here:

Required still fails on the first call, since the environment genuinely is
empty then — chained matchers have to be Optional. That is a sharp edge given
Required is the default, so it probably deserves a line in the field docs.
Each link in the chain costs roughly two iterations of Crossplane's
MaxRequirementsIterations (5), capping chains at about two levels.

Found it difficult to describe. Open for suggestions.

I have:

• Read and followed Crossplane's contribution process.
• Added or updated unit tests for my change.