Update for pgx v5

Numeric-and-decimal-support.md

@@ -7,17 +7,13 @@ The recommended solution is to use the [github.com/shopspring/decimal](https://g
 To use it add the following line to your imports:
 
 ```go
-shopspring "github.com/jackc/pgtype/ext/shopspring-numeric"
+pgxdecimal "github.com/jackc/pgx-shopspring-decimal"
 ```
 
 Then run the following to register the data type with a connection:
 
 ```go
-conn.ConnInfo().RegisterDataType(pgtype.DataType{
-  Value: &shopspring.Numeric{},
-  Name:  "numeric",
-  OID:   pgtype.NumericOID,
-})
+pgxdecimal.Register(conn.TypeMap())
 ```
 
 If you are using `pgxpool` the previous command should be run in an `AfterConnect` hook to ensure it is available on every connection.