Add some additional docs

Author: tobyzerner

docs/attributes.md

@@ -124,9 +124,13 @@ Attribute::make('name')->type(
 #### `enum`
 
 You can restrict the string to a set of possible values using the `enum` method.
+You can provide an array of strings or an array of
+[Backed Enum](https://www.php.net/manual/en/language.enumerations.backed.php)
+cases:
 
 ```php
 Attribute::make('status')->type(Str::make()->enum(['to do', 'doing', 'done']));
+Attribute::make('status')->type(Str::make()->enum(MyEnum::cases()));
 ```
 
 #### `pattern`

docs/context.md

@@ -63,7 +63,7 @@ class Context
     public function sparseFields(Resource $resource): array;
 
     // Determine whether a field has been requested in a sparse fieldset
-    public function fieldRequested(string $type, string $field, bool $default = true): bool;
+    public function fieldRequested(string $type, string $field): bool;
 
     // Determine whether a sort field has been requested
     public function sortRequested(string $field): bool;

docs/fields.md

@@ -140,6 +140,17 @@ Attribute::make('firstName')->serialize(
 );
 ```
 
+### Sparse Fieldsets
+
+[Sparse fieldsets](https://jsonapi.org/format/#fetching-sparse-fieldsets) are
+supported on endpoints as per the specification. You can exclude a field from
+the fieldset by default, so that it must be explicitly requested, by using the
+`sparse` method:
+
+```php
+Attribute::make('firstName')->sparse();
+```
+
 ## Writing
 
 By default, fields are read-only. You can allow a field to be written to in the

docs/resources.md

@@ -164,3 +164,40 @@ For Laravel applications with Eloquent-backed resources, you can extend the
 these interfaces for you. Learn more on the
 [Laravel Integration](laravel.md#eloquent-resources) page.  
 :::
+
+### Collection & Resource Actions
+
+In addition to the standard RESTful endpoints, you can create custom "action"
+endpoints for collections (`CollectionAction`) and resources (`ResourceAction`).
+
+When instantiating these classes, pass the name of the action to be used in the
+route path, and a handler which will receive the current [context](context.md)
+and optionally return a response.
+
+Collection actions will return a `204 No Content` response if nothing is
+returned by the handler. Resource actions will return a `200 OK` response
+including the resource data.
+
+```php
+use Tobyz\JsonApiServer\Context;
+use Psr\Http\Message\ResponseInterface;
+
+Endpoint\CollectionAction::make('test', function (
+    Context $context,
+): ?ResponseInterface {
+    // ...
+});
+
+Endpoint\ResourceAction::make('test', function (
+    Context $context,
+): ?ResponseInterface {
+    // ...
+});
+```
+
+The `POST` method is used by default, but you can customize this using the
+`method` method:
+
+```php
+Endpoint\CollectionAction::make(...)->method('PUT');
+```