Update gh-pages from 6400979

This trick was performed by these commands:

	mvn site &&
	export GIT_INDEX_FILE=.git/tmp-index &&
	rm -f $GIT_INDEX_FILE &&
	git add -f target/site &&
	TREE=$(git write-tree) &&
	TREE=$(git rev-parse $TREE:target/site) &&
	COMMIT=$(printf "Update gh-pages from %s" \
			$(git show -s --format=%h HEAD)" |
		git commit-tree $TREE -p refs/heads/gh-pages) &&
	git update-ref -m "Generated by mvn site" \
		refs/heads/gh-pages $COMMIT

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>