DOCSP-24188 Improve accounts example (#4057)

* DOCSP-24188 clarifying account fields

* added commas

* formatting

source/reference/operator/aggregation/exp.txt

@@ -56,20 +56,23 @@ A collection named ``accounts`` contains the following documents:
 
 .. code-block:: javascript
 
-   { _id: 1, rate: .08, pv: 10000 }
-   { _id: 2, rate: .0825, pv: 250000 }
-   { _id: 3, rate: .0425, pv: 1000 }
+   db.accounts.insertMany( [
+      { _id: 1, interestRate: .08, presentValue: 10000 },
+      { _id: 2, interestRate: .0825, presentValue: 250000 },
+      { _id: 3, interestRate: .0425, presentValue: 1000 }
+   ] )
 
 The following example calculates the effective interest rate for
 continuous compounding:
 
 .. code-block:: javascript
 
-   db.accounts.aggregate( [ { $project: { effectiveRate: { $subtract: [ { $exp: "$rate"}, 1 ] } } } ] )
+   db.accounts.aggregate( [ { $project: { effectiveRate: { $subtract: [ { $exp: "$interestRate"}, 1 ] } } } ] )
 
 The operation returns the following results:
 
 .. code-block:: javascript
+   :copyable: false
 
    { "_id" : 1, "effectiveRate" : 0.08328706767495864 }
    { "_id" : 2, "effectiveRate" : 0.08599867343905654 }