Fix custom geometry loading button, and documentation link please

[jdkio]

On the geometry viewing website, the geometry button and the "read the docu" link don't work. Here's what I wrote on slack:

You can upload the root file by clicking on button with three dots that the red up arrow is pointing to. Every time I load the page, I have to move the line marked with the blue right arrow first to see the dotted button. If it works, please fix the instructions so others will not run into the same issues. Also maybe
@Lukas Koch
can fix the page so that doesn't happen, and maybe change the ... to "load geometry" or something 🙏

Read docu also doesn't work for me. "github.com refused to connect."