cmd/link: document that -s implies -w

The Go 1.22 release notes note that the -s flag implies -w; however, the documentation makes no such reference. This updates the documentation to better match the release notes.

The Go 1.22 release notes can be found at https://tip.golang.org/doc/go1.22#linker

Fixes golang#71051

src/cmd/link/doc.go

@@ -117,7 +117,8 @@ Flags:
 	-race
 		Link with race detection libraries.
 	-s
-		Omit the symbol table and debug information.
+		Omit the symbol table and debug information. Implies the -w flag,
+		which can be negated with -w=0.
 	-tmpdir dir
 		Write temporary files to dir.
 		Temporary files are only used in external linking mode.