hg: jdk/sandbox: 8232639: Change module graph images to use SVG instead of PNG format.

[chris.hegarty at oracle.com]

Changeset: 449555c346d9
Author:    jjg
Date:      2019-10-21 11:35 -0700
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/449555c346d9

8232639: Change module graph images to use SVG instead of PNG format.
Reviewed-by: mchung, ihse

! make/Docs.gmk
! make/jdk/src/classes/build/tools/taglet/ModuleGraph.java