Add Linux commands

[Nishant-Sagar]

Changes

As the documentation was friendly for mac users I have added few Linux commands which will help a newbie Linux user to setup the project locally

Checklist

• [ ] Titles are in sentence case
• [ ] Feature names are in title case
• [ ] Words are spelled using American English
• [ ] I have checked out our style guide

[netlify[bot]]

‼️ Deploy request for posthog rejected.

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🔨 Latest commit	281cdb387bf6b94c362697ff3cfb7bd1f5f6a59f

[Twixes]

@posthog-bot please add @Nishant-Sagar for doc