added code of conduct

Cyan4973 · Cyan4973 · commit 161ecddf3ca5 · 2018-09-06T11:20:39.000-07:00
as requested by Facebook OSS program.
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
@@ -0,0 +1,5 @@
+# Code of Conduct
+
+Facebook has adopted a Code of Conduct that we expect project participants to adhere to.
+Please read the [full text](https://code.fb.com/codeofconduct/)
+so that you can understand what actions will and will not be tolerated.
