Rename CONTRIBUTING.md to UPDATE.CONTRIBUTING.md

[t1prawanta]

<script src="https://sdk.minepi.com/pi-sdk.js"></script>
<script> Pi.init({ version: "2.0", sandbox: true }) </script>

• [✓] Have you followed the contributing guidelines?
• [✓] Have you explained what your changes do, and why they add value to the Guides?

Please note: we will close your PR without comment if you do not check the boxes above and provide ALL requested information.

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[t1prawanta]

thanks again

[ahpook]

Reported as spam