Add missing period

Author: zoffixznet

doc/Language/functions.pod6

@@ -1050,7 +1050,7 @@ The default usage message is available inside C<sub USAGE> via read-only
 C<$*USAGE> variable. It will be generated based on available C<sub MAIN>
 candidates and their parameters. You can specify additional extended
 description for each candidate using C<#|(...)> Pod block to set
-L«C<WHY>|/routine/WHY»
+L«C<WHY>|/routine/WHY».
 
 =end pod