Update documentation to include more accurate dump filter
When dumping an SVN repo the dump sometimes incorrectly marks a merge of multiple revisions to a target branch as only a merge of the first revision to target. When converted this causes inaccurate contents on the target branch.
To avoid this take the SVN dump in this specific way:
svnadmin dump /path/to/repo | svndumpfilter include /path--drop-empty-revs --renumber-revs > my.dmp