Removed duplicate exercise

Removed a duplicate exercise which was 4 and 6 from Level 3. There was also a spelling change which I corrected in the same exercise.

06_Day_Loops/06_day_loops.md

@@ -472,9 +472,8 @@ for(let i = 0; i <= 5; i++){
 1. Copy countries array(Avoid mutation)
 1. Arrays are mutable. Create a copy of array which does not modify the original. Sort the copied array and store in a variable sortedCountries
 1. Sort the webTechs array and mernStack array
-1. Extract all the countries contain the word 'land' from the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and print it as array
+1. Extract all the countries containing the word 'land' from the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and print it as array
 1. Find the country containing the hightest number of characters in the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js)
-1. Extract all the countries contain the word 'land' from the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and print it as array
 1. Extract all the countries containing only four characters from the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and print it as array
 1. Extract all the countries containing two or more words from the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and print it as array
 1. Reverse the [countries array](https://github.com/Asabeneh/30DaysOfJavaScript/tree/master/data/countries.js) and capitalize each country and stored it as an array