Added some Online Development Environment Platforms links

[janup2442]

Summary of your changes

I have added a section of Online Development Environment Platforms , with some of the trusted known platform links. It's mainly for those Beginner developers who don't have a system like Laptop or Desktop to development with. I have added some legit platforms which I have tried myself , and these website will surely help , some needy student. i will update and continue to contribute to this repositories as whenever I get to any new things

Description

Checklist

• [ ] My change follows the Contributing Guidelines
• [ ] I have added only one section , Inside which added some links to platform .
• [ ] I have checked that the link that I added does NOT exist in the project already.
• [ ] I am using my tablet for contributing it's getting crashed several times while typing , I will update it soon as sort the links in Alphabetical order soon.

[janup2442]

@sdmg15 Hello sir , I have made a pull request , please read the related issue and merge it , if its helpful and good . These platforms can prove as a boon for new upcoming developers who are starting there programming journey. Do let me know if any modifications or changes needed. I will continue to contribute to this repo , as I get to know other useful stuffs