docs(subscriber): fix typo in doc comment #4

Job	Run time
gRPC-web Example	15s
gRPC-web Example	15s
Lints	51s
Lints	51s
Check	52s
Check	52s
Tests on ubuntu-latest with Rust stable	2m 44s
Tests on ubuntu-latest with Rust stable	2m 44s
Tests on macos-latest with Rust stable	6m 24s
Tests on macos-latest with Rust stable	6m 24s
Tests on windows-latest with Rust stable	4m 59s
Tests on windows-latest with Rust stable	4m 59s
Tests on ubuntu-latest with Rust 1.64.0	1m 8s
Tests on ubuntu-latest with Rust 1.64.0	2m 6s
Tests on ubuntu-latest with Rust nightly	1m 22s
Tests on ubuntu-latest with Rust nightly	1m 22s
	38m 8s

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