[io grant] Fix docs for symlink/link routines

- Fix issues with argument naming
- List new type constraints for args
- Mention symlink caveat on Windows

Rakudo impl: rakudo/rakudo@8c09c84d64
             rakudo/rakudo@da1dea2ea0
Tests:       Raku/roast@d4353b6d00
             Raku/roast@8fa49e10a4

doc/Type/IO/Path.pod6

@@ -620,25 +620,27 @@ physical storage device).
 
 =head2 routine symlink
 
-    method symlink(IO::Path:D: Str $name --> Bool)
-    sub    symlink(Str $target, Str $name --> Bool)
+    method symlink(IO::Path:D $target: IO() $link --> Bool:D)
+    sub    symlink(      IO() $target, IO() $link --> Bool:D)
 
-Create a new symbolic link named as $target (or the name of the invocant in
-the method form) to the existing file named C<$name>.
+Create a new I<symbolic> link C<$link> to existing C<$target>.
+Returns C<True> on success; L<fails|/routine/fail> with
+L<X::IO::Symlink> if the symbolic link could not be created. If C<$target>
+does not exist, creates a dangling symbolic link.
+To create a hard link, see L«C<link>|/routine/link».
 
-Both forms will return C<True> on success or L<fail|/routine/fail> with
-L<X::IO::Symlink> if the symbolic link could not be created.
+B<Note:> on Windows, creation of symbolic links may require escalated
+privileges.
 
 =head2 routine link
 
-    method link(IO::Path:D: Str $name --> Bool)
-    sub    link(Str $target, Str $name --> Bool)
+    method link(IO::Path:D $target: IO() $link --> Bool:D)
+    sub    link(      IO() $target, IO() $link --> Bool:D)
 
-Create a new link named as $target (or the name of the invocant in the
-method form) to the existing file named C<$name>.
-
-Both forms will return C<True> on success or L<fail|/routine/fail> with
-L<X::IO::Link> if the link operation could not be performed.
+Create a new I<hard> link C<$link> to existing C<$target>.
+Returns C<True> on success; L<fails|/routine/fail> with
+L<X::IO::Link> if the symbolic link could not be created.
+To create a symbolic link, see L«C<symlink>|/routine/symlink».
 
 =head2 routine unlink