ZWave Installation where is config.txt?

Installation Home Assistant OS
1

Hi!
I try to install zwave on Hass.io. The manual https://home-assistant.io/hassio/zwave/ says:

If you need GPIO on raspberry-pi3 for you Z-Wave module add follow line into config.txt:
dtoverlay=pi3-miniuart-bt

But where is the config.txt file and how can I get access to the file?

Thanks for your help

2

/boot

or put your card in another computer - It’s a FAT32 partition on the memorycard.

3

Thank you!

4

How may I mount the partition on my Mac or on my other Pi with Rasbian?