Fix exposed JavaScript problem in older pages

[oddhack]

Per https://www.khronos.org/bugzilla/show_bug.cgi?id=1404 - in some browsers, JavaScript (possibly inserted by the site framework?) appears in older ref pages like

https://www.khronos.org/opengles/sdk/docs/man/

Fixing this for very old pages isn't a priority but just to keep track of this as we migrate away from Bugzilla. The eventual solution might be to move the pages to asciidoc instead of Docbook, since we know that doesn't present any problems with e.g. the Vulkan pages, and they are far easier to edit. But a good converter for <refentry>-style Docbook is needed and I haven't found one yet.