Persistent boot.ini documentation

New changes were made to the bootini package in order to avoid the boot.ini file being rewritten every time a update is required.

The new changes are available here and were thankfully provided by mad_ady on the forums.

• The board will use boot.ini to boot.
• User made changes should be done to boot.ini.default
• After changes are made to boot.ini.default run sudo bootini command to write your changes to boot.ini
• Changes made to boot.ini will be lost when the package is upgraded.