fix broken links

Author: haesleinhuepf

README.md

@@ -70,8 +70,8 @@ If you have any questions, please use the anonymous etherpad (see email) or open
 * Block 6 - Quantitative measurements, processing folders and 3D image processing
   * Introduction to quantitative measurements
   * [3D image processing](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/image_processing/10_nd_image_data.ipynb)
-  * [Why GPU-acceleration](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/03_why_GPU_acceleration.ipynb)
-  * [GPU-accelerated image processing](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/03_why_GPU_acceleration.ipynb)
+  * [Why GPU-acceleration](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/gpu_acceleration/03_why_GPU_acceleration.ipynb)
+  * [GPU-accelerated image processing](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/gpu_acceleration/02_clesperanto.ipynb)
   * [Quantitative measurements with skimage regionprops](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/image_processing/11_quantitative_measurements.ipynb)
   * [Processing folders](http://nbviewer.jupyter.org/github/BiAPoL/Bio-image_Analysis_with_Python/blob/main/image_processing/12_process_folders.ipynb)
   * [Homework: automatic cell count](https://github.com/BiAPoL/Bio-image_Analysis_with_Python/blob/main/gpu_acceleration/homework_automatic_cellcount.pdf)