docs: Update README.md

[ChristianBieri1995]

Dear all,
While doing a PoC with K8s-Startup-Boost (which I really like by the way), I recognized that 'resourcePolicy' is missing within the Boost Part of README. Therefore, I adjusted the documentation slightly.
Cheers,
Chris

Ps: sorry for creating a new PR, I had issues with GitHub - hope everything is fine now.

[google-cla]

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[mikouaj]

Hi @ChristianBieri1995,

almost there :-) Sorry for inconveniences. There two more things pending:

• Since it is a Google repo, you need to accept Google CLA (Contributor License Agreement) - more info
• if you can make your commit message all lowercase please

Thanks!