Remove old paragraph that contradicts policy.

This summary paragraph is old from the time before we switched to using M&IE
to cover currency.  I'm unilaterally removing this paragraph because it quite
clearly conflicts with the other statements in the policy that are newer.

Travel/conservancy-travel-policy.md

@@ -152,12 +152,6 @@ for Project approval:
 * Full receipt(s) for everything, unless the travel policy does not
   require receipts (e.g., for per diem expenses).
 
-  If your receipts are in a different currency than your preferred one
-  for reimbursement, include documentation of the rate conversion (e.g., a
-  redacted credit card statement in your preferred currency).  Otherwise,
-  Conservancy will use the prevailing rate for the date of the expense for
-  conversion.
-
   Please verify that the receipts that you submit are within the attached
   travel policy requirements.  Note, however, that your Project Leadership
   Committee may have set a stricter budget than what the general