release notes add release="value" attribute to body element

[kglotfelty]

The publishing code is adding the release attribute to the body tag which the new HTML5 checker doesn't like.

For example with ciao_4.1.1_release.xml it has

<relnotes release="4.1.1">

which gets published as

<body class="withnavbar" release="4.1.1"> 

which gets flagged as an error

% publish ciao_4.1.1_release.xml  --force
Parsing [relnotes]: ciao_4.1.1_release
Created: /proj/web-cxc-dmz-prev/htdocs/ciao4.16/releasenotes/ciao_4.1.1_release.html
Validate: /proj/web-cxc-dmz-prev/htdocs/ciao4.16/releasenotes/ciao_4.1.1_release.html
HTML issues (see Doug):
1 : error - Attribute “release” not allowed on element “body” at this point.

The page can be viewed at:
  https://cxc-prev.cfa.harvard.edu/ciao4.16/releasenotes/ciao_4.1.1_release.html