Installation instructions are lacking

[dinamic]

Hey, congrats on the initiative to have the v8js re-implemented in rust.

I was having a look at the project, but couldn't find any installation instructions.

Maybe there are some, but I couldn't find them. INSTALL.md could be a suitable place? 🤔

I had a brief look at the Dockerfile, but it seems to only be installing cargo in a php container, without actually building the extension or enabling it. Maybe I'm missing something 🤔

Could you give me a hint?