grep: incorrect info in POD

In the past the grep options -e and -f possibly could not be combined but now they can. Remove incorrect POD explanatio about one option superseding the other. I only noticed this because aspell flagged "supercedes" as a spelling error.

Author: mknos

bin/grep

@@ -599,8 +599,6 @@ Treat I<pattern> as a pattern.  This option is most useful when
 I<pattern> starts with a C<-> and the user wants to avoid confusing
 the option parser.
 
-The B<-f> option supercedes the B<-e> option.
-
 =item B<-F>
 
 B<fgrep> mode.  Disable regular expressions and perform Boyer-Moore
@@ -612,8 +610,6 @@ issue).
 Treat I<pattern-file> as a newline-separated list of patterns to use
 as search criteria.
 
-the B<-f> option supercedes the B<-e> option.
-
 =item B<-g>
 
 Highlight matches.  This option causes B<grep> to attempt to use