Add a banner for the Android app.

git-svn-id: svn+ssh://svn.gnucash.org/repo/htdocs/trunk@22746 57a11ea4-9604-0410-9ed3-97b8803252fd
Bug#692981 Add "Need Help?" section to homepage.

git-svn-id: svn+ssh://svn.gnucash.org/repo/htdocs/trunk@22747 57a11ea4-9604-0410-9ed3-97b8803252fd