Document the correct semantic of the conflict count

src/de/uni_passau/fim/gitwrapper/MergeStrategy.java

@@ -12,7 +12,8 @@ public interface MergeStrategy {
      *         the left parent of the merge
      * @param right
      *         the right parent of the merge
-     * @return optionally the number of merge conflicts after the merge, if the merge was successful
+     * @return optionally the number of files with merge conflicts after the merge, if there was no general error while
+     *         merging
      */
     Optional<Integer> merge(Reference left, Reference right);
 }