use more intuitive syntax for class creation

```
create : "create node" _WS id _WS label ["@" language]
create_class: "create" _WS id
```

"node" is not user friendly language, and it's not clear why "node" is coupled with a label

I suggest:

```
create : "create" _WS [node_type _WS] _WS label ["@" language]
node_type : /class|relation/instance/annotation property/
```

No grammar file or test is named in the issue. Locate the implementation of the shown create and create_class rules, then read how node, relation, instance, annotation, and property forms are parsed; done means the syntax decision is settled and covered by grammar tests, including the resulting class-creation behavior.

Written by the indexing model from the issue text.