Update to asciidoctor-extensions 1.0.0-alpha.11

package.json

@@ -5,6 +5,6 @@
     "@antora/collector-extension": "1.0.0-alpha.4",
     "@asciidoctor/tabs": "1.0.0-beta.6",
     "@springio/antora-extensions": "1.11.1",
-    "@springio/asciidoctor-extensions": "1.0.0-alpha.10"
+    "@springio/asciidoctor-extensions": "1.0.0-alpha.11"
   }
 }