doc: gsg: Installing OpenOCD with Chocolatey on Windows environment

[soburi]

Chocolatey distributes OpenOCD, which we can use in Windows environments. Using this, we can include the installation of OpenOCD to the GSG procedure also on Windows. The GSG procedure has included installing OpenOCD on Linux/macOS so that we can align things on a level with this.

I added "openocd" to the choco install command-line and fit related descriptions.