Javadoc looks for package.html and the doc-files directory only in
the packages directory and nowhere else.
You could use the doc-files directory at the root of the source
tree and point to it using {@docRoot}. But it appears you would
like it to be outside the source tree.
You could modify Javadoc to get package.html and doc-files
from another location. If you'd like help on this, contact us at
javadoc-tool@sun.com
-Doug Kramer
Javadoc team