Clarify OTEP 4485

[martincostello]

Context: open-telemetry/opentelemetry-dotnet#6472 (comment)

It is not clear what second part of the following sentence means:

opentelemetry-specification/oteps/4485-extending-attributes-to-support-complex-values.md

Lines 203 to 205 in ec3779c

	When serializing `AnyValue` objects to JSON, it is RECOMMENDED to sort lists
	of key-value pairs lexicographically by key and apply additional settings that
	enhance serialization stability.