[bugfix/docs] Fix clear notifications API docs (#1831)

The handler is already hooked to the right path, it's just the docs that
were missing the path.

docs/api/swagger.yaml

@@ -5019,6 +5019,7 @@ paths:
             summary: Get notifications for currently authorized user.
             tags:
                 - notifications
+    /api/v1/notifications/clear:
         post:
             description: Will return an empty object `{}` to indicate success.
             operationId: clearNotifications

internal/api/client/notifications/notificationsclear.go

@@ -26,7 +26,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
-// NotificationsClearPOSTHandler swagger:operation POST /api/v1/notifications clearNotifications
+// NotificationsClearPOSTHandler swagger:operation POST /api/v1/notifications/clear clearNotifications
 //
 // Clear/delete all notifications for currently authorized user.
 //