### 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
}
		}
		if (file.begins_with("META-INF") && should_sign) {
			skip = true;
		}
		if (!skip) {
			print_line("ADDING: " + file);
			
			const bool uncompressed = info.compression_method == 0;
			zip_fileinfo zipfi = get_zip_fileinfo();
			zipOpenNewFileInZip(unaligned_apk,
					file.utf8().get_data(),
					&zipfi,
					nullptr,
					0,
					nullptr,
					0,
					nullptr,
					uncompressed ? 0 : Z_DEFLATED,
					Z_DEFAULT_COMPRESSION);
			zipWriteInFileInZip(unaligned_apk, data.ptr(), data.size());
			zipCloseFileInZip(unaligned_apk);
		}
		ret = unzGoToNextFile(pkg);
	}
	if (!invalid_abis.is_empty()) {
		add_message(EXPORT_MESSAGE_ERROR, TTR("Export"), vformat(TTR("Missing libraries in the export template for the selected architectures: %s. Please build a template with all required libraries, or uncheck the missing architectures in the export preset."), join_abis(invalid_abis, ", ", false)));
		CLEANUP_AND_RETURN(ERR_FILE_NOT_FOUND);
	}
	if (ep.step(TTR("Adding files..."), 1)) {