Changed README.md

Just a small update to the "First boot" section, added a link to "Installer customization" to clarify that the root password can be set during install as well
Merge remote-tracking branch 'upstream/master'
Changed README.md

Added a link to the installer-config.txt section with an explanation
that the default password can be set during installation as well
Merge pull request #91 from goranche/master

Added a link to the installer-config.txt section with an explanation that the default password can be set during installation as well.