Documents new custom field types

TL;DR
-----

Adds the new types of custom license fields

Details
-------

Updates the docs on custom license fields to include the "Password"
and "Enum" types. Passwords are eseentially strings that are
considered sufficiently sensitive to be masked in the UI, while enums
allow you to specify a list of options for the users to choose from.

Provides more description of each type by moving the list of types
into its own section and putting the types in a table with the name,
an explanation, and the type of widget used on the "Manage Customer"
screen.

Author: crdant

docs/vendor/licenses-adding-custom-fields.md

@@ -80,11 +80,27 @@ To create a custom license field:
    |-----------------------|------------------------|
    | Field | The name used to reference the field. This value cannot be changed. |
    | Title| The display name for the field. This is how the field appears in the Vendor Portal and the Admin Console. You can change the title in the Vendor Portal. |
-   | Type| The field type. Supported formats include integer, string, text (multi-line string), and boolean values. This value cannot be changed. |
+   | Type| The field type. This value cannot be changed. See [Understanding
+   Custom License Field Types](#understanding-custom-license-field-types) for more information.
    | Default | The default value for the field for both existing and new customers. It is a best practice to provide a default value when possible. The maximum size for a license field value is 64KB. |
    | Required | If checked, this prevents the creation of customers unless this field is explicitly defined with a value. |
    | Hidden | If checked, the field is not visible to your customer in the Replicated Admin Console. The field is still visible to you in the Vendor Portal. **Note**: The Hidden field is displayed only for vendors with access to the Replicated installers (KOTS, kURL, Embedded Cluster). |
 
+#### Understanding Custom License Field Types
+
+Each custom license field has a type that is used to validate its value. Some types change the widget used to edit the field when managing the customer.
+
+| Field                  | Description           | Widget              | 
+|-----------------------|------------------------|---------------------|
+| Integer | A whole number numeric value | text field |
+| String | Short form text that generally fits on a single line | text field |
+| Text | Longer form text that may contain multiple lines | text area |
+| Boolean | True or false | checkbox |
+| Password | A short string of text that is masked on display | password ||
+| Enum | Provides a list of possible values | dropdown |
+
+String, Text, Password, and Enum types are all represented as strings in the license.
+
 ### Update Custom License Fields
 
 To update a custom license field:
@@ -138,4 +154,4 @@ To delete a custom license field:
    If you enable **Preserve License Values**, you can create a new field with the same name and `type` as the deleted field to reinstate the preserved values.
    :::
 
-1. Follow the instructions in the dialog and click **Delete**.
+1. Follow the instructions in the dialog and click **Delete**.