[wwwdocs] Remove Bullets for "Platforms" and "Testing" in the Sidebar

[DJ Delorie]

> In the light of this, and the resurrection of the "Installation" link, do
> you think it's okay to keep the bullets?  Should we format this somewhat
> differently, perhaps?

Can we at least be consistent?  Some of the sub-items use a bullet,
others use ellipses.

Also, "(tentative timeline)" should be "Tentative Timeline" to be
consistent with the other sub-items.

(personally, I use <small> around sub-items like that, as long as
they're rare)