docs(advanced): add link to pio cli install instructions

[negue]

What this changes

This is just adds a hint where/how to get the CLI, cause it took me way to long to find the actual site / instructions for it 😬

I hope changing the docs files alone are enough unless this also need a build as well, but I think thats what the workflow is for

How it was verified

• python scripts/test_native.py passes
• pio run -e awtrix, pio run -e awtrix_s3_octal and pio run -e awtrix_s3_quad build
• Tested in the simulator (pio run -e native_sim)
• Tested on hardware — board:

Checklist

• New behaviour has a host test in test/, or it genuinely cannot run off-device
• src/core/ stayed portable (no Arduino, FastLED or board headers)
• Documentation in docs/ updated for any new field, endpoint or setting
• Regenerated any checked-in generated file this change invalidates
  (see the table in CONTRIBUTING.md)