add instruction for Debian system

[ticapix]

Small edit to add instruction for Debian (apt based) distribution.

Tested on a NUC7i3BNB with Proxmox

root@pve:~/keys# export LD_LIBRARY_PATH=/opt/Intel/iclsClient/lib/
root@pve:~/keys# ./Intel-SA-00086-Recovery-Tool
Retrieving RSA/ ECC EK Certificate from iCLS backend
Recovery successful. Attempting to read new EK certificate from NV
Reading RSA EK Certificate from NV Index
Downloading intermediate and root CA certificates
Validating EK certificate chain
Downloading certificate revocation list information
Checking certificate revocation list
Endorsement key certificate download/ validation complete
root@pve:~/keys#