RFR: 8199705: Docs.gmk needs to be updated to remove the -html5 option

[Bhavesh Patel]

Hi,

     This is a simple fix to Docs.gmk. A fix for JDK-8182765 
<https://bugs.openjdk.java.net/browse/JDK-8182765> was pushed recently 
to javadoc enabling it to generate HTML 5 output by default. This makes 
the "-html5" option, defined in the initial set of javadoc options in 
Docs.gmk, redundant. I have removed the -html5  option. Please review 
this fix.


JBS: https://bugs.openjdk.java.net/browse/JDK-8199705

Webrev: http://cr.openjdk.java.net/~bpatel/8199705/webrev.00/ 
<http://cr.openjdk.java.net/%7Ebpatel/8199705/webrev.00/>