Add a gif explaining how to Contribute to this repository

[zyllus17]

I know I sound like a noob because I am one right now.

I created an Extension Pack for the Flutter Community and I believe it has a pretty neat UI with GIF explaining everything. Here is the link - Ultimate Flutter Extension Pack
There aren't many Readme available for Extension Packs so I thought of adding it to the list.
I read the contribution guidelines and I am still learning about git and how to contribute to other people's repository.

TL:DR
If you guys can add a GIF in the Contribution Guidelines on how to do it, it would be great!

[zyllus17]

Never mind literally I guess. I learnt it on my own