Sort required fields before others

[cbandy]

I noticed that required fields were always rendered last. It appears they are intended to be first. This inverts the sort criteria and adds a test.

crdoc/pkg/builder/properties.go

Lines 48 to 50 in 47f3978

	// orderedPropertyKeys returns the keys of m alphabetically ordered
	// keys in required will be placed first
	func orderedPropertyKeys(required []string, m map[string]apiextensions.JSONSchemaProps, isResource bool) []string {

[roee88]

Nice, thanks for the fix!