### Godot version

4.0 stable

### System information

Fedora, RX 590

### Issue description

I made a dictionary, and instead of using `:` to separate between key and value, i accidentally used `=`.
The error message was not clear at all `Parse Error: Expected identifier or string as LUA-style dictionary key.` 

I don't think assuming that people know how dictionaries are made in LUA is reasonable. And if this is not about LUA the programming language, i don't even know what this is about :D

I think this error should be replaced with something of the sort "Please use `:` as separator instead of `=` in your dictionary"

### Steps to reproduce

Paste this code in a script:

```

var dict = {
	1 = "lala"
}
```

Observe the error message
![image](https://user-images.githubusercontent.com/7917475/224549538-38ea25aa-ba75-431e-868b-0733a53b90ad.png)


### Minimal reproduction project

see above
String doc;
	int line = p_line;
	DocLineState state = DOC_LINE_NORMAL;
	while (comments.has(line - 1)) {
		if (!comments[line - 1].new_line || !comments[line - 1].comment.begins_with("##")) {
			break;
		}
		line--;
	}
	String space_prefix;
	if (comments.has(line) && comments[line].comment.begins_with("##")) {
		int i = 2;
		for (; i < comments[line].comment.length(); i++) {
			if (comments[line].comment[i] != ' ') {
				break;
			}
		}
		space_prefix = String(" ").repeat(i - 2);
	}
	while (comments.has(line)) {
		if (!comments[line].new_line || !comments[line].comment.begins_with("##")) {
			break;
		}
		String doc_line = comments[line].comment.trim_prefix("##");
		doc += _process_doc_line(doc_line, doc, space_prefix, state);
		line++;
	}
	return doc;
}
void GDScriptParser::get_class_doc_comment(int p_line, String &p_brief, String &p_desc, Vector<Pair<String, String>> &p_tutorials, bool p_inner_class) {