docs: Fix installation command on macOS for stackablectl #275

Job	Run time
General Pull Request Checks / Run Cargo Udeps	10m 36s
General Pull Request Checks / Run Cargo Deny (advisories)	47s
General Pull Request Checks / Run Clippy	3m 45s
General Pull Request Checks / Run RustDoc	3m 54s
General Pull Request Checks / Run Cargo Deny (bans licenses sources)	40s
General Pull Request Checks / Run Rustfmt	27s
General Pull Request Checks / Run Cargo Tests	3m 36s
General Pull Request Checks / All tests passed	1s
Build stackablectl for x86_64-unknown-linux-gnu	3m 14s
Build stackablectl for aarch64-unknown-linux-gnu	3m 57s
Build stackablectl for x86_64-apple-darwin	4m 11s
Build stackablectl for aarch64-apple-darwin	3m 59s
	39m 7s

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