Show Changelog by default for "View version x.y.z details" links for Plugin...

Show Changelog by default for "View version x.y.z details" links for Plugin updates. Props linuxologos. Fixes #19208

git-svn-id: https://core.svn.wordpress.org/trunk@19711 1a063a9b-81f0-0310-95a4-ce76da25c4cd