docs/manual: use bugs.buildroot.org for bugtracker

Now that we have a bugs.buildroot.org CNAME for bugzilla lets use that in
the manual as well.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

docs/manual/contribute.txt

@@ -25,7 +25,7 @@ for more information on obtaining a Buildroot git tree.
 === Reproducing, analyzing and fixing bugs
 
 A first way of contributing is to have a look at the open bug reports in
-the https://bugs.busybox.net/buglist.cgi?product=buildroot[Buildroot bug
+the https://bugs.buildroot.org/buglist.cgi?product=buildroot[Buildroot bug
 tracker]. As we strive to keep the bug count as small as possible, all
 help in reproducing, analyzing and fixing reported bugs is more than
 welcome. Don't hesitate to add a comment to bug reports reporting your

docs/manual/resources.txt

@@ -42,7 +42,7 @@ better as it will reach more people, both developers and users.
 Bug tracker::
 +
 Bugs in Buildroot can be reported via the mailing list or alternatively
-via the https://bugs.busybox.net/buglist.cgi?product=buildroot[Buildroot
+via the https://bugs.buildroot.org/buglist.cgi?product=buildroot[Buildroot
 bugtracker]. Please refer to xref:reporting-bugs[] before creating a bug
 report.