Add Appendices Parent for nav

Author: rwinch

modules/ROOT/nav.adoc

@@ -15,14 +15,15 @@
 * xref:repository-projections.adoc[]
 * xref:query-by-example.adoc[]
 * xref:auditing.adoc[]
-* xref:repository-namespace-reference.adoc[]
-* xref:repository-populator-namespace-reference.adoc[]
-* xref:repository-query-keywords-reference.adoc[]
-* xref:repository-query-return-types-reference.adoc[]
 * xref:custom-conversions.adoc[]
 * xref:entity-callbacks.adoc[]
 * xref:is-new-state-detection.adoc[]
 * xref:kotlin-coroutines.adoc[]
 * xref:kotlin-extensions.adoc[]
 * xref:kotlin.adoc[]
 * xref:upgrade.adoc[]
+* Appendices
+** xref:repository-namespace-reference.adoc[]
+** xref:repository-populator-namespace-reference.adoc[]
+** xref:repository-query-keywords-reference.adoc[]
+** xref:repository-query-return-types-reference.adoc[]