### Godot version

3.5.1.stable, v4.0.beta.custom_build [0a87ead64]

### System information

Ubuntu 22.04.1

### Issue description

For example, if project has name "300spartans", we can't enter the "org.godotengine.300spartans" to "Unique Name" field. We get the error "Invalid package name: A digit cannot be the first character in a package segment". But , if we enter "org.godotengine.$genname", there will be no error message. When exporting, the name will be set as "org.godotengine.spartans" without "300" in beginning, but user will not be informed about it. I think, it is not very good. It may not be worth making changes to the source code, but mention it in the documentation.

### Steps to reproduce

See issue description.

### Minimal reproduction project

N/A
MutexLock lock(device_lock);
	return devices.size();
}
String EditorExportPlatformAndroid::get_options_tooltip() const {
	return TTR("Select device from the list");
}
String EditorExportPlatformAndroid::get_option_label(int p_index) const {
	ERR_FAIL_INDEX_V(p_index, devices.size(), "");
	MutexLock lock(device_lock);
	return devices[p_index].name;
}
String EditorExportPlatformAndroid::get_option_tooltip(int p_index) const {
	ERR_FAIL_INDEX_V(p_index, devices.size(), "");
	MutexLock lock(device_lock);
	String s = devices[p_index].description;
	if (devices.size() == 1) {
		
		
		
		s = devices[p_index].name + "\n\n" + s;
	}
	return s;
}
Error EditorExportPlatformAndroid::run(const Ref<EditorExportPreset> &p_preset, int p_device, int p_debug_flags) {