Merge pull request #45 from TopEFT/comment-xsec-units

Comments to the xsec yml

topcoffea/params/xsec.yml

@@ -1,4 +1,8 @@
-# Notes about the numbers:
+# Important notes:
+#   - All numbers are in pb
+#   - If you add a new number, it must include a comment saying where it comes from
+
+# Historical notes about the original set of numbers:
 #   - Most of the XSECs match the numbers used in TOP-19-001 (presumably drawn from a variety of twiki pages and talks)
 #   - The WWTo2L2Nu number comes from https://twiki.cern.ch/twiki/bin/viewauth/CMS/SummaryTable1G25ns
 #   - Thus, most of these numbers a more or less placeholders for now, till an "official" set becomes available