Translate README to Portuguese

[tobySolutions]

Please translate the README.md file located at https://github.com/GaiaNet-AI/gaianet-node/blob/main/README.md into Portuguese. Please specify if you are translating to Brazilian Portuguese or European Portuguese, if it matters for your project.

The translated file should be at: https://github.com/GaiaNet-AI/gaianet-node/blob/main/README-pt.md

Please ensure the translation is accurate and maintains the original meaning and intent of the document.

[Bridgetamana]

Is this still up for grabs?
@tobySolutions