fix old links

[liya-oz]

These links appear to be broken:

1. explore/Week1/README.md line 162 - About your web browser

2. explore/Week2 /README.md line 58 For more information about responsive design, check this article: Responsive Design.

Suggested Solution:

• Delete the link About your web browser;
• Update the link Responsive Design to Modern Responsive Design

I find this article useful because it offers simple explanations and interactive examples that make learning responsive design easier.