Update README.md

Author: huhuhang

README.md

@@ -12,10 +12,10 @@ NumPy is the foundation of scientific computing in Python. This Skill Tree provi
 
 |   Index | Name                                                                            | Difficulty   | Repo                                                               | Practice                                                           |
 |---------|---------------------------------------------------------------------------------|--------------|--------------------------------------------------------------------|--------------------------------------------------------------------|
-|       1 | [Quick Start with NumPy](https://labex.io/courses/quick-start-with-numpy)       | ★☆☆          | [🔗 Repo](https://github.com/labex-labs/quick-start-with-numpy)    | [🚀 Start Lab](https://labex.io/courses/quick-start-with-numpy)    |
-|       2 | [NumPy Practice Labs](https://labex.io/courses/numpy-practice-labs)             | ★☆☆          | [🔗 Repo](https://github.com/labex-labs/numpy-practice-labs)       | [🚀 Start Lab](https://labex.io/courses/numpy-practice-labs)       |
-|       3 | [NumPy Practice Challenges](https://labex.io/courses/numpy-practice-challenges) | ★☆☆          | [🔗 Repo](https://github.com/labex-labs/numpy-practice-challenges) | [🚀 Start Lab](https://labex.io/courses/numpy-practice-challenges) |
-|       4 | [100 NumPy Exercises](https://labex.io/courses/100-numpy-exercises)             | ★★☆          | [🔗 Repo](https://github.com/labex-labs/100-numpy-exercises)       | [🚀 Start Lab](https://labex.io/courses/100-numpy-exercises)       |
+|       1 | [Quick Start with NumPy](https://labex.io/courses/quick-start-with-numpy)       | Beginner     | [🔗 Repo](https://github.com/labex-labs/quick-start-with-numpy)    | [🚀 Start Lab](https://labex.io/courses/quick-start-with-numpy)    |
+|       2 | [NumPy Practice Labs](https://labex.io/courses/numpy-practice-labs)             | Beginner     | [🔗 Repo](https://github.com/labex-labs/numpy-practice-labs)       | [🚀 Start Lab](https://labex.io/courses/numpy-practice-labs)       |
+|       3 | [NumPy Practice Challenges](https://labex.io/courses/numpy-practice-challenges) | Beginner     | [🔗 Repo](https://github.com/labex-labs/numpy-practice-challenges) | [🚀 Start Lab](https://labex.io/courses/numpy-practice-challenges) |
+|       4 | [100 NumPy Exercises](https://labex.io/courses/100-numpy-exercises)             | Intermediate | [🔗 Repo](https://github.com/labex-labs/100-numpy-exercises)       | [🚀 Start Lab](https://labex.io/courses/100-numpy-exercises)       |
 
 ## More