Add Muhammad Hamza to contribution list

[Hamza1610]

Before submitting this pull request, please go through the checklist below.
If you're doing something in the checklist, put an x inside [ ] so that - [ ] becomes - [x]

• I have added a screenshot from browser with my changes
• [ x] There are no errors in the console
• [ x] I had fun going through this tutorial and learned on the way
• [ x] There are some things I'd like to improve in this tutorial. I have written them below.

Proposed improvement
There is no docuementation of how to generate contribution list.
chmod +x scripts/generate-cards.sh then ./scripts/generate-cards.sh

[kelvinator07]

You should create and change only one file your-name.html

[Hamza1610]

You should create and change only one file your-name.html

I figured that out, but when I was following the docs, I found out that the there is no reference to how to make the script to compile the contributors name executable.