Single-Source

[Patrick Venture]

Brad;

While working on updating the documentation, which holds a
clang-format example in it, within the markdown, I was curious if
there was a single-source of truth w.r.t configurations of this
nature?  I imagine it hasn't been an issue yet, but I'm going to
update clang-format files to use the header inclusion, once we settle
on the exact pattern, and it'd be useful to have a single-source file
where I could make the change, and copy that file out into places --
since I'm not sure of a reasonable automated approach.

Any suggestions or thoughts would be appreciated.

Patrick