Merge pull request ossf#66 from ossf/oxford

Note that we use Oxford commas

Author: david-a-wheeler

secure_software_development_fundamentals.md

@@ -25,11 +25,14 @@ We can quickly fix significant mistakes, but we otherwise want to only implement
 
 The learning approach is designed to potentially support many users (with a potential of 10-15 million), so all problems (including knowledge checks) must be completely automated. There are no plans to use cohorts, discussions, or anything else requiring human instructors (because that doesn’t scale well). In most cases the knowledge checks are 1-2 multiple choice questions. They will generally have a random *order* of answers, but not Randomized *values* of answer (no Python script is involved).
 
+**Contributor Guidance**
+
 This document is written to be easily understood by its audience (in this case, software developers). In general, in this document:
 
 * Use contractions (unless you want special emphasis on something).
 * Use logical quotation, not typographical quotation. Quotations only include what is quoted. For more, see [Wikipedia: Logical quotation on Wikipedia](https://en.wikipedia.org/wiki/Wikipedia:Logical_quotation_on_Wikipedia).
 * Use pronouns, especially *you*.
+* Use Oxford commas.
 * Cite sources.
 
 For more, see [5 Stupid Grammar Rules You Should Never Follow Because They Make Your Writing Worse](https://www.inc.com/minda-zetlin/5-stupid-grammar-rules-you-should-never-follow-because-they-make-your-writing-wo.html) and [6 Grammar Superstitions: The Never-Never Rules](https://wac.colostate.edu/docs/books/grammar/chapter6.pdf).