manpage enhancement in 9.3.1 on Linux

Hi together,
I'm new to this list an hope to be in the right place to request a
documentation enhancement in the Linux manpage of pg_createcluster. I
was wondering what happens to an existing datadir (specified with the
--datadir option) filled with the content of a previously existing
database/cluster. Is it backed up? Is the content used, i.e. datadirs
pluggable to different clusters/databases created with pg_createcluster?
Is it deleted? One and a halve sentence or a link to extended
documentation in the section explaining the datadir option would be nice
and not too much for a manpage in my opinion.
I refer to the tag REL9_3_1 of the git fetch-URL
https://github.com/postgres/postgres.git.

All the best,
K. Richter