Amend readme for constants

README.md

@@ -76,6 +76,7 @@ Table of Contents
       * [Reload](#reload)
       * [Exists](#exists)
       * [Enums](#enums)
+      * [Constants](#constants)
     * [FAQ](#faq)
         * [Won't compiling models for a huge database be very slow?](#wont-compiling-models-for-a-huge-database-be-very-slow)
         * [Missing imports for generated package](#missing-imports-for-generated-package)
@@ -1223,6 +1224,41 @@ still be able to use your generated library, and it will still work as expected,
 to get the tests to pass in this event is to either use a parsable enum value or use a regular column
 instead of an enum.
 
+### Constants
+
+The models package will also contain some structs that contain all of the table and column
+names harvested from the database at generation time.
+
+For table names they're generated under `models.TableNames`:
+
+```go
+// Generated code from models package
+var TableNames = struct {
+	Messages  string
+	Purchases string
+}{
+	Messages:  "messages",
+	Purchases: "purchases",
+}
+
+// Usage example:
+fmt.Println(models.TableNames.Messages)
+```
+
+```go
+// Generated code from models package
+var MessageColumns = struct {
+	ID         string
+	PurchaseID string
+}{
+	ID:         "id",
+	PurchaseID: "purchase_id",
+}
+
+// Usage example:
+fmt.Println(models.MessageColumns.ID)
+```
+
 ## FAQ
 
 #### Won't compiling models for a huge database be very slow?