docs: update preload default value (#1818)

doc/API.md

@@ -396,7 +396,7 @@ Additionally, there are a number or properties that allow configuration of diffe
 | `elementRef`       | `false` | Return element references in addition to the target                                                                                     |
 | `restoreScroll`    | `false` | Scrolls elements back to before axe started                                                                                             |
 | `frameWaitTime`    | `60000` | How long (in milliseconds) axe waits for a response from embedded frames before timing out                                              |
-| `preload`          | `false` | Any additional assets (eg: cssom) to preload before running rules. [See here for configuration details](#preload-configuration-details) |
+| `preload`          | `true` | Any additional assets (eg: cssom) to preload before running rules. [See here for configuration details](#preload-configuration-details) |
 | `performanceTimer` | `false` | Log rule performance metrics to the console                                                                                             |
 
 ###### Options Parameter Examples