### 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
DOC_LINE_NORMAL,
	DOC_LINE_IN_CODE,
	DOC_LINE_IN_CODEBLOCK,
};
static String _process_doc_line(const String &p_line, const String &p_text, const String &p_space_prefix, DocLineState &r_state) {
	String line = p_line;
	if (r_state == DOC_LINE_NORMAL) {
		line = line.strip_edges(true, false);
	} else {
		line = line.trim_prefix(p_space_prefix);
	}
	String line_join;
	if (!p_text.is_empty()) {
		if (r_state == DOC_LINE_NORMAL) {
			if (p_text.ends_with("[/codeblock]")) {
				line_join = "\n";
			} else if (!p_text.ends_with("[br]")) {
				line_join = " ";
			}
		} else {
			line_join = "\n";
		}
	}