RFR(XXS): 8189919: Update link to license in Docs.gmk

[mark.reinhold at oracle.com]

2017/10/26 9:11:08 -0700, iris.clark at oracle.com:
> Please review this small change to update the link to the
> 
> Specification license referenced by the JavaDoc API.  For
> 
> JDK 10, we should reference the 10 redirect.
> 
> Bug:
> 
>  
> 
>     8189919: Update link to license in Docs.gmk
> 
>     https://bugs.openjdk.java.net/browse/JDK-8189919
> 
>  
> 
> webrev:
> 
>  
> 
>     http://cr.openjdk.java.net/~iris/8189919/webrev/

Looks good to me.

- Mark