docs: cmd typo

[strikoza]

for easier copy/pasting the command

What this PR does / why we need it:

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.

[JStickler]

[docs team] LGTM, thanks for taking the time to update the docs!

[JStickler]

@strikoza You need to sign the CLA before I can merge this PR.

[strikoza]

@JStickler done - signed.

[JStickler]

@strikoza I was just checking to see which branches to backport this PR to, and realized that I fixed this same issue earlier today while working on the file in #15462. So closing this, as it's already fixed.

But thanks so much for taking the time to submit this PR. We always appreciate it when people take the time to improve the documentation.