Fix broken link to accrualPeriodicity

Author: philipashlock

Diff for: v1.1/schema.md

@@ -247,7 +247,7 @@ Dataset Fields {#Dataset}
 **Cardinality** | (0,1)
 **Required** | No
 **Accepted Values** | ISO 8601 Repeating Duration (or `irregular`)
-**Usage Notes** | Must be an ISO 8601 repeating duration unless this is not possible because the accrual periodicity is completely irregular, in which case the value should simply be `irregular`.  The value should not include a start or end date but rather simply express the duration of time between data publishing.  For example, a dataset which is updated on an annual basis would be `R/P1Y`; every three months would be `R/P3M`; weekly would be `R/P1W`; and daily would be `R/P1D`.  Further examples and documenation [can be found here](/iso8601_guidance.md#accrualperiodicity).  
+**Usage Notes** | Must be an ISO 8601 repeating duration unless this is not possible because the accrual periodicity is completely irregular, in which case the value should simply be `irregular`.  The value should not include a start or end date but rather simply express the duration of time between data publishing.  For example, a dataset which is updated on an annual basis would be `R/P1Y`; every three months would be `R/P3M`; weekly would be `R/P1W`; and daily would be `R/P1D`.  Further examples and documenation [can be found here](/iso8601_guidance#accrualperiodicity).  
 **Example** |  `{"accrualPeriodicity":"R/P1Y"}`
 
 {: .table .table-striped #bureauCode}