fix duplicated white space and typo [skip ci]

docs/guide/concept-properties.md

@@ -9,7 +9,7 @@ to a `label` property. You could use the following code to achieve this task:
 $object->label = trim($label);
 ```
 
-The drawback of the above code is that you have to call `trim()` everywhere in your code where you met set the `label`
+The drawback of the above code is that you have to call `trim()` everywhere in your code where you might set the `label`
 property. If in the future, the `label` property gets a new requirement, such as the first letter must be captialized, you would again have to modify every bit of code that assigns a value to `label`. The repetition of code leads to bugs and is a practice you want to avoid as much as possible.
 
 To solve this problem, Yii introduces a base class called [[yii\base\Object]] that supports defining properties