More documentation about how to install Google Optimize

**Is your feature request related to a problem? Please describe.**
It is unclear about what needs to be installed to get this library to work.

The docs mention
> Using the useGoogleOptimize hook requires that you've [installed Google Tag Manager](https://support.google.com/optimize/answer/6314801?hl=en) and created [Google Optimize](https://marketingplatform.google.com/about/optimize/) test cases.

But clicking that link, there is note that says to use the Optimize js install:
> We strongly recommend using the [optimize.js](https://support.google.com/optimize/answer/9692472) installation method as it offers the best performance and is the easiest way to install Optimize.

So what do I need to install to get this to work? GTM or Optimize or both?

**Describe the solution you'd like**
Please update documentation on readme to describe how to get this working as it appear the linked documentation may have changed without knowing.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A

Update the README section for the useGoogleOptimize hook, starting with its existing Google Tag Manager and Google Optimize links. Check the linked installation guidance and clarify whether GTM, Optimize, or both are required; the documentation is done when a reader can follow one unambiguous setup path.

Written by the indexing model from the issue text.