fix: headers, license

[Irene-123]

Hello there, I have updated the readme by fixing the headers, adding a license tag and some points. The changes are quite basic, if we need to do any other major changes, do let me know. Thank you

[yixinBC]

nice job!

[yixinBC]

but there are still some improvements

[Irene-123]

but there are still some improvements

Tell me some rough improvements, I'll add it

[yixinBC]

but there are still some improvements

Tell me some rough improvements, I'll add it

look through my code reviews above.