Typo causing broken link (#280)

This error's link
(https://neo4j.com/docs/status-codes/current/errors/gql-errors/#_42n26)
is not working because it's not listed in the content-nav file due to a
typo.

Author: lidiazuin

modules/ROOT/content-nav.adoc

@@ -231,7 +231,7 @@
 **** xref:errors/gql-errors/42N21.adoc[]
 **** xref:errors/gql-errors/42N22.adoc[]
 **** xref:errors/gql-errors/42N24.adoc[]
-**** xref:errors/gql-errors/42I26.adoc[]
+**** xref:errors/gql-errors/42N26.adoc[]
 **** xref:errors/gql-errors/42N28.adoc[]
 **** xref:errors/gql-errors/42N29.adoc[]
 **** xref:errors/gql-errors/42N31.adoc[]