see issue #4540

[gist of report with link checks](https://gist.github.com/finanalyst/47673157b55de202c62b612eaafe1d48#file-gistfile1-txt)

doc/Language/5to6-perlvar.rakudoc

@@ -47,7 +47,7 @@ C<.shift> does not).
 =head3 X<$LIST_SEPARATOR, $"|Other languages,$" (Perl)>
 
 Currently, there is no equivalent of the List Separator variable in Raku.
-Design document L<S28|https://design.raku.org/S28.html> says there isn't one,
+Design document L<S28|https://github.com/Raku/old-design-docs/blob/master/S28-special-names.pod> says there isn't one,
 so you probably don't want to hold your breath.
 
 =head3 X<$PROCESS_ID, $PID, $$|Other languages,$$ (Perl)>
@@ -176,7 +176,7 @@ S28 suggests $*EMERGENCY_MEMORY, but it does not yet exist.
 =head3 $OSNAME, $^O
 
 This is somewhat unclear. It probably depends on what you mean by "the name of
-the operating system" as design document L<S28|https://design.raku.org/S28.html>
+the operating system" as design document L<S28|https://github.com/Raku/old-design-docs/blob/master/S28-special-names.pod>
 has three different suggestions, all of which
 give different answers.
 

doc/Language/about.rakudoc

@@ -30,7 +30,7 @@ L<Raku/doc-website on GitHub|https://github.com/Raku/doc-website>.
 
 For a quick introduction to Raku Pod, see L<Raku Pod|/language/pod>.
 
-For historic details about the Raku Pod specification, see L<Synopsis 26, Documentation|https://design.raku.org/S26.html>.
+For historic details about the Raku Pod specification, see L<Synopsis 26, Documentation|https://github.com/Raku/old-design-docs/blob/master/S26-documentation.pod>.
 
 For information on how to contribute to the documentation, please
 read L<CONTRIBUTING.md|https://github.com/Raku/doc/blob/main/CONTRIBUTING.md>.

doc/Language/modules.rakudoc

@@ -9,7 +9,7 @@
 A module is usually a source file or set of source files that expose Raku
 constructs N<Technically a module is a set of I<compunits> which are usually
 files but could come from anywhere as long as there is a I<compunit repository>
-that can provide it. See L<S11|https://design.raku.org/S11.html>.>.
+that can provide it. See L<S11|https://github.com/Raku/old-design-docs/blob/master/S11-modules.pod>.>.
 
 Modules are typically packages (L<classes|/language/objects#Classes>,
 L<roles|/language/objects#Roles>, L<grammars|/type/Grammar>),

doc/Language/pod.rakudoc

@@ -79,7 +79,7 @@ any whitespace is used inside the angle brackets.
 
 All option keys and values must be constants since Rakudoc is a
 specification language, not a programming language. Specifically, option
-values cannot be closures. See L<Synopsis 2|https://design.raku.org/S02.html>
+values cannot be closures. See L<Synopsis 2|https://github.com/Raku/old-design-docs/blob/master/S02-bits.pod>
 for details of the various
 Raku pair notations.