Fix rewrite rule to actually redirect sub-pages to their new location.

My previous version redirected them to the contribute/how/user_experience
parent page.

wiki/src/.htaccess

@@ -7,7 +7,7 @@ RewriteRule ^bugs/FireGPG_may_be_unsafe/?$ doc/encryption_and_privacy/FireGPG_su
 RewriteRule ^chat/?$ support/chat [R]
 RewriteRule ^contribute/easy_tasks/?$ contribute/starter_tasks [R]
 RewriteRule ^contribute/how/donate/?$ donate [R]
-RewriteRule ^contribute/how/user_interface contribute/how/user_experience [R]
+RewriteRule ^contribute/how/user_interface(.*) contribute/how/user_experience$1 [R]
 RewriteRule ^contribute/l10n_tricks/git-clean-po.sh contribute/l10n_tricks/git-clean-po [R]
 RewriteRule ^contribute/signing_key_revocation/?$ doc/about/openpgp_keys/signing_key_revocation [R]
 RewriteRule ^contribute/working_together/roles/front_desk/?$ contribute/working_together/roles/help_desk [R]