Suggest adding code highlighting

[chenzhitong]

Suggest adding code highlighting

Such as

GitHub:

docs.neo.org:

[chenzhitong]

Replace ```c# with ```cs

https://github.com/neo-project/neo-dev-portal/blob/645418f9fcd07a791b472dbad9519fabd8d61e6b/docs/n3/develop/write/basics.md?plain=1#L7-L16

https://docusaurus.io/docs/markdown-features/code-blocks#supported-languages

[apisit]

Thanks for spotting this. Updated. It will be in the next release.