[Documentation] clarifies 'in C-locale'

[HughParsonage]

Adds a sentence to man/setorder.Rd to close #1996.

[codecov-io]

Codecov Report

Merging #2387 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2387      +/-   ##
==========================================
+ Coverage   91.24%   91.29%   +0.05%     
==========================================
  Files          62       62              
  Lines       11978    11978              
==========================================
+ Hits        10929    10935       +6     
+ Misses       1049     1043       -6

Impacted Files	Coverage Δ
src/forder.c	94.47% <0%> (+0.78%)	⬆️

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[MichaelChirico]

Well, that's not exactly true. I have in mind users for whom neither C nor R locales are English. Maybe worth clarifying ("commonly"/"in English locales"/etc)

[mattdowle]

@HughParsonage This is great! I started a quick edit and it ended up being quite an expansion. Please could you check it before I pull and merge. I'll wait for you. @MichaelChirico I'll wait for you too since you commented above.

[HughParsonage]

I decided to put this part in Details as Matt's extra additions were important but a bit too lengthy for the Description (you couldn't see the Usage section with it in). Also meant this part of the documentation could use less abbreviated language and hence be a bit clearer.

[MichaelChirico]

looks great!

[mattdowle]

Yep - great!
( I meant to squash as I merged this one. The merge button is sticky from its last setting and I just pressed it. I'll leave it and move on this time, but I'll remember next time hopefully. )