Update man page of gnt-cluster regarding file-storage-dir
Update man page of gnt-cluster regarding file-storage-dir

This extends the description of 'gnt-cluster init' and
'gnt-cluster modify' with respect to the file storage
directory.

Signed-off-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>
Reviewed-by: Thomas Thrainer <98bdeac947eb8ca18146e9ce7f092788ec242cd1@google.com>

mbakke/ganeti,leshchevds/ganeti,mbakke/ganeti,bitemyapp/ganeti,apyrgio/ganeti,yiannist/ganeti,apyrgio/snf-ganeti,andir/ganeti,yiannist/ganeti,mbakke/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,leshchevds/ganeti,dimara/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,apyrgio/snf-ganeti,ganeti/ganeti,apyrgio/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,ganeti/ganeti,dimara/ganeti,onponomarev/ganeti,yiannist/ganeti,andir/ganeti,ganeti/ganeti