Add conduct document

Author: rafaelfranca

CODE_OF_CONDUCT.md

@@ -0,0 +1,11 @@
+# Contributor Code of Conduct
+
+The Rails team is committed to fostering a welcoming community.
+
+**Our Code of Conduct can be found here**:
+
+https://rubyonrails.org/conduct
+
+For a history of updates, see the page history here:
+
+https://github.com/rails/website/commits/main/_pages/conduct.html