added small hint in README

Author: theRealSuperMario

README.md

@@ -139,6 +139,21 @@ to install/update.
     \usepgfplotslibrary{dateplot}
     ```
 
+4. Optional: clean up the figure before exporting to tikz using the `clean_figure` command.
+    ```python
+    import matplotlib.pyplot as plt
+    import numpy as np
+
+    #... do your plotting
+
+    import tikzplotlib
+    tikzplotlib.clean_figure()
+    tikzplotlib.save("test.tex")
+    ```
+    The command will remove points that are outside the axes limits, simplify curves and reduce point density for the specified target resolution.
+    
+    The feature originated from the [matlab2tikz](https://github.com/matlab2tikz/matlab2tikz) project and is adapted to matplotlib.
+
 ### Contributing
 
 If you experience bugs, would like to contribute, have nice examples of what