Update two defunct tigris.org links

[Daniel Sahlberg]

Hi,

As described in the subject, replace two links to tigris.org with current
links.

cvs2svn is based on r1879904 in Subversion's repository. (It was suggested
by Stefan Sperling at
http://mail-archives.apache.org/mod_mbox/subversion-dev/202007.mbox/%3C20200715075907.GY86429%40ted.stsp.name%3E
)

issue_3457 links through the Subversion website redirect to Apache.org's
JIRA. (I'm not 100% sure it is the correct issue but I believe the issue
ids were carried over in the migration to JIRA, anyway please review!)

Kind regards,
Daniel Sahlberg
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.red-bean.com/pipermail/svnbook-dev/attachments/20210823/f56c7240/attachment.htm>
-------------- next part --------------
Index: ch06-server-configuration.xml
===================================================================
--- ch06-server-configuration.xml	(revision 6039)
+++ ch06-server-configuration.xml	(working copy)
@@ -3914,7 +3914,7 @@
             of the mechanisms that one might employ to accomplish this
             replication fall short in one way or
             another<footnote><para><ulink
-            url="http://subversion.tigris.org/issues/show_bug.cgi?id=3457"
+            url="https://subversion.apache.org/issue3457"
             /> tracks these problems.</para></footnote>.  Many teams
             don't use Subversion's locking features at all, so this
             may be a nonissue for you.  Sadly, for those teams which