fix(doc): update EnvResourceDetector specification link #4223

Job	Run time
docs	1m 42s
coverage	3m 47s
cargo-deny	26s
external-types (opentelemetry)	1m 6s
lint	4m 14s
msrv	4m 19s
external-types (opentelemetry-sdk)	1m 18s
non-default-examples (opentelemetry-otlp/examples/basic-otlp)	39s
test (stable)	8m 29s
test (beta)	8m 45s
	34m 45s

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