Co-authored-by: Tomasz Kantecki <tomasz.kantecki@intel.com>

kat-app: improve README.md format

Keystream generation function using GFNI was not always
used when GFNI instructions are available.

The goal of this application is to showcase
how to use the ipsec-mb API by encrypting
several buffers with AES-GCM, using the new burst API.

This is required to set CMAKE_EXPORT_COMPILE_COMMANDS before
configuring lib and app targets to generate cppcheck database