grep.1: Use Fl for -print0

[Josiah Frentsos]

Index: grep.1
===================================================================
RCS file: /cvs/src/usr.bin/grep/grep.1,v
retrieving revision 1.51
diff -u -p -r1.51 grep.1
--- grep.1      26 Jun 2022 10:57:36 -0000      1.51
+++ grep.1      3 Jan 2023 16:52:05 -0000
@@ -304,7 +304,7 @@ file name.
 This option makes the output unambiguous, even in the presence of file
 names containing unusual characters like newlines.
 This is similar to the
-.Ar -print0
+.Fl print0
 option in
 .Xr find 1 .
 .El