doc: add missing period

PR-URL: nodejs#49094
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Moshe Atlow <[email protected]>

Author: Trott

doc/api/policy.md

@@ -6,6 +6,6 @@
 
 > Stability: 1 - Experimental
 
-The former Policies documentation is now at [Permissions documentation][]
+The former Policies documentation is now at [Permissions documentation][].
 
 [Permissions documentation]: permissions.md#policies