Add CODE_OF_CONDUCT.md (#46204)

Add the file so that GitHub puts a link in the repository's side bar and
shows it in the community standards tab. The text is taken from the
canonical source to give a brief background, but links to the document
for the full text.

Author: efd6

CODE_OF_CONDUCT.md

@@ -0,0 +1,15 @@
+# Community Code of Conduct
+
+Elastic is dedicated to providing a positive experience for everyone in
+Elastic's Open Source Community, regardless of age, caste, citizenship,
+disability, education, ethnicity, gender identity or expression, immigration
+status, level of experience, neurodiversity, physical appearance or body size,
+nationality, socio-economic status, sexual orientation, race, or religion
+(or lack thereof). Our products are distributed by design, and with many
+languages, perspectives, and cultures, it's easy to lose something in
+translation. Respect cultural differences, and don't assume malice. We do not
+tolerate harassment or discrimination in any form.
+
+Please see Elastic's [Open Source Community Code of Conduct]
+(https://www.elastic.co/community/codeofconduct) for the full text of the
+code.