minor: typos in `docs/LANGUAGE.md`

[jameskim0987]

I found some minor typos while reading through the docs.

https://github.com/jameskim0987/cyphernetes/blob/main/docs/LANGUAGE.md

1. "we can use the the resource's singular name" -> "we can use the resource's singular name" ( remove the redundant the )
2. "Unlike kubectl, labels in Cyphernetes are also case-insensitive" -> "Unlike kubectl, labels in Cyphernetes are case-insensitive" ( remove "also". When I initially read through this statement, the also threw me off. I think removing the also would bring a bit more clarity )
3. "be followed by a `RETURN`` clause:" -> "be followed by a `RETURN` clause:" ( remove the extra ` )