Validate / Introduce Requirement re "newline" at line end

          Super minor whitespace nit:

Originally posted by @StephenButtolph in #1211 (comment)

I'm used to hitting "RETURN" at the end-of-line, even if it is the last line of the file.

nit

To my knowledge, several tools depend on the existents of a "newline", otherwise they do not recognize the line as such.

There's even a standard:

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206

Suggestion

Introduce a requirement to always add a newline at the end of a line, even if it is the last line of a document.

[StephenButtolph]

There is a trailing newline. That nit was because it was introducing a second trailing newline. I'm totally down for adding a linter to enforce exactly one trailing newline though.

Oh... A double-RETURN, I see...

adding a linter to enforce exactly one trailing newline though.

+1