docs: Fix installation command on macOS for stackablectl #47

Job	Run time
General Pull Request Checks / Run Clippy	3m 16s
General Pull Request Checks / Run Cargo Deny (advisories)	47s
General Pull Request Checks / Run Cargo Deny (bans licenses sources)	43s
General Pull Request Checks / Run RustDoc	3m 50s
General Pull Request Checks / Run Rustfmt	42s
General Pull Request Checks / Run Cargo Tests	3m 35s
General Pull Request Checks / Run Cargo Udeps	8m 6s
General Pull Request Checks / All tests passed	1s
	21m 0s

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