Updated introduction.md (#2809)

* Updated introduction.md

Corrected some spelling mistakes.

* Update introduction.md

exercises/concept/elons-toy-car/.docs/introduction.md

@@ -35,8 +35,8 @@ class Car {
 ```
 
 One can optionally assign an initial value to a field.
-If a field does _not_ specify an initial value, it wll be set to its type's default value.
-An instance's field values can be accessed and updated using dot-notation.
+If a field does _not_ specify an initial value, it will be set to its type's default value.
+An instance's field values can be accessed and updated using dot notation.
 
 ```java
 class Car {