FINERACT-2354: [doc] Re-aging functional description

Author: somasorosdpc

fineract-doc/src/docs/en/chapters/features/index.adoc

@@ -10,3 +10,4 @@ include::interest-rate-change-progressive-loans.adoc[leveloffset=+1]
 include::contract-termination.adoc[leveloffset=+1]
 include::loan-charges.adoc[leveloffset=+1]
 include::journal-entry-aggregation.adoc[leveloffset=+1]
+include::re-ageing.adoc[leveloffset=+1]