sh.1: update history + spdx + linter error

[concussious]

When I first discovered the history section of the BSD manual, I knew I had stumbled into a cathedral. In just a few sentances, it provides the reader with a idea of how Chestertons fence came to be there, creating context to begin understanding the deeper spiritual meaning of POLA and consistency in the design philosophy of our community.

Reinforce this elegance by adding the release when Almquists shell first appeared in BSD. While here, tag spdx and remove a redundant macro.

History source: www.in-ulm.de/~mascheck/various/ash/#bsd

[mhorne]

Seems fine, but maybe @bsdimp can confirm the change to the HISTORY section.

[concussious]

Thanks @mhorne!