Fix linking to the previous and the next day

Also fix the the output codeblock for the excercise Level 3.

10_Day_Sets_and_Maps/10_day_Sets_and_Maps.md

@@ -434,13 +434,12 @@ const countries = ['Finland', 'Sweden', 'Norway']
    // Your output should look like this
    console.log(mostSpokenLanguages(countries, 3))
    ```
-
+   ```js
       [
       { 'English': 91 },
       { 'French': 45 },
       { 'Arabic': 25 }
       ]
-
    ```
 
 
@@ -448,4 +447,3 @@ const countries = ['Finland', 'Sweden', 'Norway']
 
 
 [<< Day 9](../09_Day_Higher_order_functions/09_day_higher_order_functions.md) | [Day 11>>](../11_Day_Destructuring_and_spreading/11_day_destructuring_and_spreading.md)
-```