Added code to writing-to-files

[raghuchandan1]

Please fill in this pull request template before submitting

1. This pull request resolves #17

(^Fill in the issue number after #)

2. Description

Added the tutorial for writing into a file and added a minor change in reading-files to close the file

3. Fill in checklist by marking [x]

• [x] I've read the CONTRIBUTING.md
• [x] I was assigned to this issue
• [x] My code is formatted using required linting
• [x] I've run my code locally and checked it works

[funbeedev]

@raghuchandan1 looks great, thank you!