update your 2015 article about SSH security

[piramiday]

@stribika, it would be really interesting to know what your current best SSH practices are -- five years after your excellent post:

https://stribika.github.io/2015/01/04/secure-secure-shell.html

any further suggestions? new threats to beware? :raised_hand_with_fingers_splayed:

[LTIOfficial]

Especially given the major changes that TLS1.3 brings to the table.