Update the wiki to include documentation for the collapse input type

Dialog-Manager.md

@@ -41,6 +41,7 @@ Returns a count of how many currently open unique dialogs there are.
 ### `InputType`
 This type represents a string with any of the following values:
 - [`checkbox`](#checkbox)
+- [`collapse`](#collapse)
 - [`details`](#details)
 - [`divider`](#divider)
 - [`input`](#input)
@@ -52,6 +53,13 @@ This type represents a string with any of the following values:
 | `label`  | `string` | The user-facing label for the input.
 | `defaultValue` | `boolean?` | The default value for the input, if not provided it defaults to `false`.
 
+#### `Collapse`
+| Property | Type | Description
+| -------- | ---- | -----------
+| `summary` | `string` | The user-facing label for the collapse. This is the text that does not disappear when collapsed.
+| `inputs` | [AskInput](#askinput)[] | The list of inner inputs of the collapse. Allows all existing input types.
+| `content` | `string?` | The text-content for the collapsed area. Unused if `inputs` is provided.
+
 #### `details`
 Used to display a simple paragraph of text in between inputs.