### 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
result += '\n';
					}
					r_state = DOC_LINE_IN_CODEBLOCK;
					buffer_start = from;
				}
			} break;
			case DOC_LINE_IN_CODE: {
				int pos = line.find("[/code]", from);
				if (pos < 0) {
					process = false;
					break;
				}
				from = pos + 7;
				r_state = DOC_LINE_NORMAL;
			} break;
			case DOC_LINE_IN_CODEBLOCK: {
				int pos = line.find("[/codeblock]", from);
				if (pos < 0) {
					process = false;
					break;
				}
				from = pos + 12;
				if (pos == 0) {
					line_join = "\n";
				} else {
					result += line.substr(buffer_start, pos - buffer_start) + '\n';
				}
				result += "[/codeblock]";
				if (from < len) {
					result += '\n';