Include files, apps or libraries.
<s:include file="posts/hellow-world.sunsed" />
the content of hello-world.sunsed...
<include>ignores hidden files unless you use the
Path to a file in your account.
Include built-in apps and libraries.
Produce an error if the file/app does not exist.
Include all files inside a folder.
Recursively include files. Only useful when
folder="" attribute is used.