Fix wrong path name

Change-Id: I79ed336058ffa9e182d3332acfeda8d6526c6b43
Reviewed-on: https://gerrit.libreoffice.org/63432Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>
Tested-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>

emfio/README

-It contains emfio/source/emfeader which is used for "Insert->Picture->From File".
+It contains emfio/source/reader which is used for "Insert->Picture->From File".