Fix some errors in Readme.md and some performance optimization (#646)

I like this project very much, it's great, but there are some errors in readme.md
And the following about performance optimization
Optimize token generation with strings. Builder
Replace inefficient string concatenation with strings. Builder for token generation.
This improves performance by reducing memory allocations during string creation.
Using WriteByte also avoids unnecessary type conversions from character to string.

Co-authored-by: guocheng <cheng.guo@quantix.ae>