Update hyperlink in Readme file [GSSoC'21]

[vineetsingh0809]

Describe the bug
The hyperlink of the GSSoC project is not working.

To Reproduce
Steps to reproduce the behavior:

1. Go to Readme.MD file
2. Scroll down to Important Notice.
3. Click on the hyperlink of GSSoC.
4. See an error

Expected behavior
It should be open the main page of GirlScript Summer of Code.
I will change the code to fix this error

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

[vineetsingh0809]

Hey @ambujraj .....
Could you assign this issue to me