fix(doc): update EnvResourceDetector specification link #4226

Job	Run time
cargo-deny	26s
docs	1m 40s
external-types (opentelemetry)	1m 1s
external-types (opentelemetry-sdk)	1m 13s
coverage	3m 47s
lint	5m 11s
msrv	4m 15s
non-default-examples (opentelemetry-otlp/examples/basic-otlp)	38s
test (stable)	8m 21s
test (beta)	8m 36s
	35m 8s

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