Fix documentation typo (#568)

Author: otakustay

index.d.ts

@@ -206,7 +206,7 @@ export type CommonOptions<EncodingType> = {
 	/**
 	You can abort the spawned process using [`AbortController`](https://developer.mozilla.org/en-US/docs/Web/API/AbortController).
 
-	When `AbortController.abort()` is called, [`.isCanceled`](https://github.com/sindresorhus/execa#iscanceled) becomes `false`.
+	When `AbortController.abort()` is called, [`.isCanceled`](https://github.com/sindresorhus/execa#iscanceled) becomes `true`.
 
 	@example
 	```

readme.md

@@ -711,7 +711,7 @@ Type: [`AbortSignal`](https://developer.mozilla.org/en-US/docs/Web/API/AbortSign
 
 You can abort the spawned process using [`AbortController`](https://developer.mozilla.org/en-US/docs/Web/API/AbortController).
 
-When `AbortController.abort()` is called, [`.isCanceled`](#iscanceled) becomes `false`.
+When `AbortController.abort()` is called, [`.isCanceled`](#iscanceled) becomes `true`.
 
 #### windowsVerbatimArguments