Fix exposed JavaScript problem in older pages

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 \-style Docbook is needed and I haven't found one yet.

Start with the linked Khronos Bugzilla report and inspect the older OpenGL ES reference pages at khronos.org/opengles/sdk/docs/man/. Compare the generated pages with the Vulkan pages, then determine whether the exposed JavaScript can be fixed in the current Docbook output or requires a Docbook-to-Asciidoc migration. Done means the older pages no longer expose the unwanted JavaScript, with the conversion path understood if migration is required.

Written by the indexing model from the issue text.