Suggestion: Add "Description:" header to defconfig file

Currently we use the name of the board profile directory to give some clue to users what is the purpose of that defconfig, i.e.: nsh, usbnsh, netnsh, timer, kostest, etc.

But in some case it is not enough, people familiar to NuttX will know what that kostest does, but for a newcomer it doesn't make much sense.

Also now on ESP32S3 we will have two USB Console options: USB Console using USB-JTAG-SERIAL peripheral (that we will call usbconsole) and USB Console using USB OTG Device (that we will call usbnsh).