Update formatting in README.md

I have successfully Reviewed MR !41 for drupal version 9.5.x-dev.We can see following changes on README.md file after applying MR.
1. Introduction comes at the start of the page with the name of Admin Toolbar.
2. Only the first letter of content title's changed to capslock.
3. "This project has been sponsored by" title changed to
"Supporting organizations". And also added 3 more supporting organizations to this group .
4. 3 more current maintainers added to the new file of README.md .

Thanks

Automatically closed - issue fixed for 2 weeks with no activity.