Added Letter_Z.cpp

[Parul1923]

Issue Id you have worked upon -

342

Briefly explain your program logic -

The required pattern is printed by using two nested loops.

Screenshots(Attach 2 screenshots of your own input and output) -

Checklist:

Eg - If your code follow the below guidelines. Kindly change [] to [x]

All the conditions should be fulfilled for considering your code for merging -

• [x] I have mentioned the question as comment in my solution file.
  

• [x] My code follows the guidelines of this project.
  

• [x] I have performed a self-review of my own code.
  

• [x] I have commented my code.
  

• [x] My code gives the correct output.
  

• [x] I confirm that I have not copied the code from anywhere. In case its found that I have copied even after successful merge then I can be banned from the repository and hacktoberfest.
  

• [x] I affirm that I strictly follow contributing guidelines and code of conduct.

[SarthakKeshari]

@Parul1923, Kindly fill the checklist and write issue id as #342