Add Siemens logo

[ektrah]

/cc @epaulson

[epaulson]

There have been some deployment hiccups of late, so we'll have to watch to see if this actually goes live or if we have to fix it manually.

[gtfierro]

This is updated on the Brick website! (https://brickschema.org/consortium/)

I am still working on figuring out how to solve the deployment issue but I can at least reliably update the site manually