Fix Sat Nov 11 09:08:42 UTC 2017 option in doc

wiki/src/blueprint/monthly_report.mdwn

@@ -62,7 +62,7 @@ Publishing
   publication:
 
   - Set the `meta date=` directive to today's date in RFC 2822 format
-    (e.g. `date --rfc-email`).
+    (e.g. `date --rfc-2822`).
   - Move report to `news/report_YEAR_MO.mdwn`.
   - Commit and push.
   - Tweet about the report: