Use long PGP ID for debian install instructions

[nh2]

On https://github.com/IntelRealSense/librealsense/blame/57e623cd7d5f3912ffae5af86e104d93577fedb0/doc/distribution_linux.md#L17 it recommends

sudo apt-key adv --keyserver keys.gnupg.net --recv-key 6F3EFCDE

short PGP keys are trivial to forge (32-bit integers), so it would be better if you could use the long PGP ID instead in the instrall instructions.

[dorodnic]

Hi @nh2
Thank you for the suggestion. We will check how our current infrastructure would allow this.

[RealSense-Customer-Engineering]

[Realsense Customer Engineering Team Comment]
hi @nh2,
thanks for input, PR created #1978 for this.
let me close this ticket here and please feel free to open new ticket if any question.

[nh2]

Thanks!