I'm using this repository to record what I am finding out about using OpenOCD.
It is mainly for my own benefit, but maybe other people will find it useful too.
esp32/README.md has information on using an FTDI2232H minimodule to connect to an esp32 for debugging.
nrf51822/readme.md has info on re-flashing a Bluefruit LE Sniffer from Adafruit.