Update CONTRIBUTING.md Section 2.7.f i SSH for Mac - creating folder

[elisetvy]

Fixes #6240

What changes did you make?

• Update instructions for creating ~/.ssh folder

Why did you make the changes (we will use this info to test)?

• To avoid confusion for developers creating their initial SSH key
• For Reviewers: Do not review changes locally, rather, review changes at https://github.com/elisetvy/hfla-site/blob/update-contributing-ssh-6240/CONTRIBUTING.md

Screenshots of Proposed Changes Of The Website (if any, please do not screen shot code changes)

Visuals before changes are applied

Visuals after changes are applied

[github-actions[bot]]

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Note that CONTRIBUTING.md cannot previewed locally; rather it should be previewed at this URL:

https://github.com/elisetvy/website/blob/update-contributing-ssh-6240/CONTRIBUTING.md  

[marioantonini]

Review ETA: EOD 5/8/24

[Jperparas]

review ETA: EoD 5/9