### 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
static const int EXPORT_FORMAT_AAB = 1;
static const char *APK_ASSETS_DIRECTORY = "res://android/build/assets";
static const char *AAB_ASSETS_DIRECTORY = "res://android/build/assetPacks/installTime/src/main/assets";
static const int DEFAULT_MIN_SDK_VERSION = 21; 
static const int DEFAULT_TARGET_SDK_VERSION = 32; 
#ifndef ANDROID_ENABLED
void EditorExportPlatformAndroid::_check_for_changes_poll_thread(void *ud) {
	EditorExportPlatformAndroid *ea = static_cast<EditorExportPlatformAndroid *>(ud);
	while (!ea->quit_request.is_set()) {
		
		{
			
			if (!ea->plugins_changed.is_set()) {
				Vector<PluginConfigAndroid> loaded_plugins = get_plugins();
				MutexLock lock(ea->plugins_lock);
				if (ea->plugins.size() != loaded_plugins.size()) {
					ea->plugins_changed.set();
				} else {
					for (int i = 0; i < ea->plugins.size(); i++) {
						if (ea->plugins[i].name != loaded_plugins[i].name) {
							ea->plugins_changed.set();
							break;
						}
					}
				}
				if (ea->plugins_changed.is_set()) {
					ea->plugins = loaded_plugins;
				}
			}
		}