fix(package): remove postinstall script, relax engine constraints (#81

)

This PR:

- Removes `postinstall` npm script. I was thinking about `prepare`, but
for some reason added `postinstall`. Anyway, both are meh, so ended up
with manual `npm run install:all` command.
- Adds `install:all` npm script to install dependencies for the package
itself, as well as for **docs** and **benchmarks** to avoid issues when
contributing. Also there's a short explanation in README now.
- Relaxes engine (node) constraints a bit: from `>=18.16.0 <=20` to
`>=18 to <=20`.

Resolves #80

README.md

@@ -149,6 +149,18 @@ And in the end we get the following output with the AST, which can then be manip
 ```
 </details>
 
+## Development
+
+Fork, clone, then instead of `npm install` run:
+
+```sh
+npm run install:all
+```
+
+> **Note**
+>
+> This will install dependencies for the package itself, and also for **docs** and **benchmarks** packages. This is due to limitations of the current repository setup and needed to avoid problems with eslint that runs on pre-commit hook.
+
 ## License
 
 [MIT](LICENSE).