Update the htaccess.ref-guide-antora for release 9.1.0
diff --git a/themes/solr/templates/htaccess.ref-guide-antora b/themes/solr/templates/htaccess.ref-guide-antora
index 76b75d2..3cbad93 100644
--- a/themes/solr/templates/htaccess.ref-guide-antora
+++ b/themes/solr/templates/htaccess.ref-guide-antora
@@ -1,2 +1,2 @@
-Redirect 302 /guide/solr/9_0 /guide/solr/latest
-Redirect 302 /guide/solr/index.html /guide/solr/latest/index.html
+Redirect 302 /guide/solr/9_1 /guide/solr/latest
+Redirect 301 /guide/index.html /guide/solr/latest/index.html