docs(x/ecocredit): clarify basket exponent usage to eliminate rounding (

#752)

proto/regen/ecocredit/basket/v1/tx.proto

@@ -36,12 +36,13 @@ message MsgCreate {
   string display_name = 3;
 
   // exponent is the exponent that will be used for converting credits to basket
-  // tokens and for bank denom metadata. An exponent of 6 will mean that 10^6
-  // units of a basket token will be issued for 1.0 credits and that
-  // this should be displayed as one unit in user interfaces. The exponent
-  // must be >= the precision of the credit type to minimize the need for
-  // rounding (rounding may still be needed if the precision changes to be greater
-  // than the exponent).
+  // tokens and for bank denom metadata. It also limits the precision of
+  // credit amounts when putting credits into a basket. An exponent of 6 will
+  // mean that 10^6 units of a basket token will be issued for 1.0 credits and that
+  // this should be displayed as one unit in user interfaces. It also means
+  // that the maximum precision of credit amounts is 6 decimal places so that
+  // the need to round is eliminated. The exponent must be >= the precision of
+  // the credit type at the time the basket is created.
   uint32 exponent = 4;
 
   // disable_auto_retire allows auto-retirement to be disabled.