Change link on Pipeline Release Notes page

[barentsen]

Once Doug is back and checks in his latest version of the pipeline release notes, we should change the link that points to KSCI-19080-001.pdf into KSCI-19080-002.pdf and make the link text less obscure.

[kcolon]

and update headings and sidebar on the data release notes page as per @mrtommyb's request:

sidebar on the data release notes page is funky when it is longer than the page. I suggest we remove submenus from it

[barentsen]

Link on pipeline release notes page has been fixed.

[barentsen]

Submenus have been removed from the data release notes page by changing e.g.

## Features and events

into

<h2>Features and events</h2>

(which is a bit of a hacky solution, unfortunately)