Replace CFL logo in downloadable certificates

[evemartin]

The old CFL logo needs to be replaced with the new registered CFL logo in the downloadable Rapid Router completion cerificates. These can be found on Gitbook here and here, and the files referenced on Gitbook can be found here in the shared Google Drive. We will have to update the Drive files and also the screenshots on the GItbook pages.

Here is the new registered CFL logo file:

The full set of registered CFL logos can be found here in the shared Google Drive.