We have only one release note now, so keep the struct simple.

Conflicts:
	framework/Release/test/Horde/Release/Unit/ReleaseTest.php
	horde/docs/RELEASE_NOTES
	imp/docs/RELEASE_NOTES
	ingo/docs/RELEASE_NOTES
	kronolith/docs/RELEASE_NOTES
	mnemo/docs/RELEASE_NOTES
	nag/docs/RELEASE_NOTES
	turba/docs/RELEASE_NOTES