diff: Document the --no-dereference option.

Also, --no-dereference should not imply --recurse.

MFC after:	3 days
Sponsored by:	Klara, Inc.
Reviewed by:	allanjude
Differential Revision:	https://reviews.freebsd.org/D45779

usr.bin/diff/diff.1

@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 7, 2024
+.Dd June 29, 2024
 .Dt DIFF 1
 .Os
 .Sh NAME
@@ -52,6 +52,7 @@
 .Op Fl -ignore-space-change
 .Op Fl -initial-tab
 .Op Fl -minimal
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -normal
 .Op Fl -rcs
@@ -83,6 +84,7 @@
 .Op Fl -ignore-space-change
 .Op Fl -initial-tab
 .Op Fl -minimal
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -normal
 .Op Fl -paginate
@@ -110,6 +112,7 @@
 .Op Fl -ignore-space-change
 .Op Fl -initial-tab
 .Op Fl -minimal
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -normal
 .Op Fl -paginate
@@ -139,6 +142,7 @@
 .Op Fl -ignore-space-change
 .Op Fl -initial-tab
 .Op Fl -minimal
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -normal
 .Op Fl -paginate
@@ -171,6 +175,7 @@
 .Op Fl -initial-tab
 .Op Fl -minimal
 .Op Fl -new-file
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -normal
 .Op Fl -paginate
@@ -201,6 +206,7 @@
 .Op Fl -ignore-blank-lines
 .Op Fl -ignore-case
 .Op Fl -minimal
+.Op Fl -no-dereference
 .Op Fl -no-ignore-file-name-case
 .Op Fl -strip-trailing-cr
 .Op Fl -suppress-common-lines
@@ -497,6 +503,8 @@ lines from FILE2
 .El
 .It Fl -ignore-file-name-case
 ignore case when comparing file names
+.It Fl -no-dereference
+do not follow symbolic links
 .It Fl -no-ignore-file-name-case
 do not ignore case when comparing file names (default)
 .It Fl -normal

usr.bin/diff/diff.c

@@ -368,7 +368,6 @@ main(int argc, char **argv)
 					optarg);
 			break;
 		case OPT_NO_DEREFERENCE:
-			rflag = true;
 			noderef = true;
 			break;
 		case OPT_VERSION: