doc: use serial comma in report docs

Refs: nodejs/node#11321
Refs: nodejs/node#17384

PR-URL: nodejs/node#43394
Reviewed-By: Darshan Sen <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Harshitha K P <[email protected]>
Reviewed-By: Mohammed Keyvanzadeh <[email protected]>

Author: tniessen

doc/api/report.md

@@ -524,7 +524,7 @@ Node.js report completed
 
 When a report is written, start and end messages are issued to stderr
 and the filename of the report is returned to the caller. The default filename
-includes the date, time, PID and a sequence number. The sequence number helps
+includes the date, time, PID, and a sequence number. The sequence number helps
 in associating the report dump with the runtime state if generated multiple
 times for the same Node.js process.
 
@@ -551,7 +551,7 @@ Special meaning is attached to `stdout` and `stderr`. Usage of these
 will result in report being written to the associated standard streams.
 In cases where standard streams are used, the value in `directory` is ignored.
 URLs are not supported. Defaults to a composite filename that contains
-timestamp, PID and sequence number.
+timestamp, PID, and sequence number.
 
 `directory` specifies the filesystem directory where the report will be written.
 URLs are not supported. Defaults to the current working directory of the