Add a margin to the `Welcome Pull Request` section in the mobile view

[YoshithaRathnayake]

Describe the bug

• Currently, in the mobile view in the Welcome Pull Request section the margin of right and left sides are very low

To Reproduce
Steps to reproduce the behavior:

1. Go to 'DEV SITE'
2. Scroll down to 'Welcome Pull Request Section'
3. See error (mobile view)

Expected behavior
Add a margin to the Welcome Pull Request section

Screenshots
If applicable, add screenshots to help explain your problem.

Are you working on it?
Yes

[YoshithaRathnayake]

Shall I work on this ?