docs: add documentation comments for apps and paging types

- add doc comments to `AppsEndpoint`, `App` struct, and the `Get` method
in `apps.go`.
- add doc comments to the `Page` struct in `page.go`.
- add doc comments to `PagingRequest`, `PagingOption`, and paging helper
functions in `pagingRequest.go`.

apps.go

@@ -9,16 +9,27 @@ const (
 	appsPath = "/apps"
 )
 
+// AppsEndpoint provides access to apps in an Onspring instance.
 type AppsEndpoint struct {
 	client *Client
 }
 
+// App represents an Onspring app
 type App struct {
 	Href string `json:"href"`
 	Id   int    `json:"id"`
 	Name string `json:"name"`
 }
 
+// Get retrieves a paginated list of apps from the Onspring API.
+//
+// Parameters:
+//   - ctx: The context for the request
+//   - pagingOpts: Optional paging configuration functions (e.g., ForPageNumber, WithPageSize)
+//
+// Returns:
+//   - Page[App]: A page of apps with pagination metadata
+//   - error: An error if the request fails
 func (p *AppsEndpoint) Get(ctx context.Context, pagingOpts ...PagingOption) (Page[App], error) {
 	pagingRequest := &PagingRequest{
 		pageNumber: 1,