feat(cpp): add empty() for unordered_set

Closes #8048

Author: ylevental

content/cpp/concepts/unordered-set/terms/empty/empty.md

@@ -0,0 +1,73 @@
+---
+Title: C++ Unordered Set empty()
+Description: The C++ `empty()` method, when used with an unordered_set, checks if the unordered_set container is empty or not.
+---
+
+The C++ `empty()` method, when used with an unordered_set, checks if the unordered_set container is empty or not.
+
+## Syntax
+
+```cpp
+unordered_set_name.empty()
+```
+
+The `empty()` method does not take any parameters and returns a boolean value:
+
+- `true`: if the unordered_set is empty.
+- `false`: if the unordered_set is not empty.
+
+## Example
+
+```cpp
+#include <iostream>
+#include <unordered_set>
+#include <string>
+
+int main() {
+  std::unordered_set<std::string> groceries;
+
+  if (groceries.empty()) {
+    std::cout << "The grocery list is empty!\n";
+  } else {
+    std::cout << "The grocery list is not empty.\n";
+  }
+
+  groceries.insert("Milk");
+  groceries.insert("Eggs");
+
+  if (groceries.empty()) {
+    std::cout << "The grocery list is empty!\n";
+  } else {
+    std::cout << "The grocery list is not empty.\n";
+  }
+
+  return 0;
+}
+```
+
+## Codebyte Example
+
+```codebyte/cpp
+#include <iostream>
+#include <unordered_set>
+
+int main() {
+  std::unordered_set<int> my_set;
+
+  if (my_set.empty()) {
+    std::cout << "The unordered_set is empty.\n";
+  } else {
+    std::cout << "The unordered_set is not empty.\n";
+  }
+
+  my_set.insert(10);
+
+  if (my_set.empty()) {
+    std::cout << "The unordered_set is empty.\n";
+  } else {
+    std::cout << "The unordered_set is not empty.\n";
+  }
+
+  return 0;
+}
+```