GPG signatures missing for versions 1.8.5 and 1.8.6

[M-Reimer]

This is a follow up to the following issues:
#458
#518

I'll immediately close my issue after this one is created and if the signatures are in place, #458 can be closed also.

The current packaging process for Arch Linux requires a GPG signature to exist. The following signatures are missing:
https://downloads.arduino.cc/cores/staging/avr-1.8.5.tar.bz2.asc
https://downloads.arduino.cc/cores/staging/avr-1.8.6.tar.bz2.asc

Would be great if someone could sign these packages and upload the signature files.