Fix: Typo on redis note

What does this MR do?

Fix a typo on Redis auth note.

Author checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, follow the instructions in the "Reviewer Roulette" section of the Danger Bot MR comment, as per the Distribution experimental MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes (Does not apply)
• Documentation created/updated (Does not apply)
• Tests added/updated (Does not apply)
• Integration tests added to GitLab QA (Does not apply)
• Equivalent MR/issue for omnibus-gitlab opened (Does not apply)
• Equivalent MR/issue for Gitlab Operator project opened (see Operator documentation on impact of Charts changes) (Does not apply)
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file. (Does not apply)