docs: add Homebrew installation to README

[Peredery]

What does this PR do?

Adds documentation to the README for installing Text Embeddings Inference on Apple Silicon (M1 and so on) via a Homebrew prebuilt binary:

brew install text-embeddings-inference

This makes it easier for Mac users to get started without needing to build from source.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline?
• Was this discussed/approved via a GitHub issue or the forum? Please add a link to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the documentation guidelines.
• Did you write any new necessary tests? If applicable, did you include or update the insta snapshots?

Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

[alvarobartt]

Thanks @Peredery, maybe you can also include it on https://github.com/huggingface/text-embeddings-inference/blob/main/docs/source/en/local_metal.md too?

[Peredery]

Thanks @Peredery, maybe you can also include it on https://github.com/huggingface/text-embeddings-inference/blob/main/docs/source/en/local_metal.md too?

Hi! Thanks for review, I added to this file :)

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.