docs: form builder number field table unformatted (#8915)

### What?
This PR aims to fix an issue in the form-builder plugin page - in the
`number` field table, where an issue with one of the columns makes the
whole table unformatted. [See issue
here](https://payloadcms.com/docs/beta/plugins/form-builder#number).

### Why?
As it stands, the whole table is being rendered without any formatting,
making understanding it very difficult.

### How?
Changes to `docs/plugins/form-builder.mdx`

docs/plugins/form-builder.mdx

@@ -343,12 +343,12 @@ Maps to a `checkbox` input on your front-end. Used to collect a boolean value.
 Maps to a `number` input on your front-end. Used to collect a number.
 
 | Property       | Type     | Description                                          |
-| -------------- | -------- | ---------------------------------------------------- | --- | -------------- | ------ | ------------------------------- |
+| -------------- | -------- | ---------------------------------------------------- |
 | `name`         | string   | The name of the field.                               |
 | `label`        | string   | The label of the field.                              |
-| `defaultValue` | string   | The default value of the field.                      |
+| `defaultValue` | number   | The default value of the field.                      |
 | `width`        | string   | The width of the field on the front-end.             |
-| `required`     | checkbox | Whether or not the field is required when submitted. |     | `defaultValue` | number | The default value of the field. |
+| `required`     | checkbox | Whether or not the field is required when submitted. |
 
 ### Message