Add vector page to navigation

Author: stefano-ottolenghi

modules/ROOT/content-nav.adoc

@@ -58,6 +58,7 @@
 ** xref::values-and-types/spatial.adoc[]
 ** xref::values-and-types/lists.adoc[]
 ** xref::values-and-types/maps.adoc[]
+** xref::values-and-types/vector.adoc[]
 ** xref::values-and-types/working-with-null.adoc[]
 ** xref::values-and-types/casting-data.adoc[]
 ** xref:values-and-types/ordering-equality-comparison.adoc[]