doc: fixed minor typo in runbook-update-ca-certs.md

[sfc-gh-pfus]

Serial number for instruction to save file and submit PR should be 6, instead of 5.

Description

SNOW-XXX Please explain the changes you made here.

Checklist

• [ ] Created tests which fail without the change (if possible)
• [ ] Extended the README / documentation, if necessary

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 75.38%. Comparing base (ec3e828) to head (c81d0a3).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1122 +/- ## ======================================= Coverage 75.38% 75.38% ======================================= Files 53 53 Lines 11243 11243 ======================================= Hits 8476 8476 Misses 2767 2767 ```

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