Update README.md

Cython related installation issues -> added a tip

README.md

@@ -26,8 +26,14 @@ pip install numpy Cython scipy h5py nibabel matplotlib Pillow numexpr tornado lx
 git clone https://github.com/VisionandCognition/NHP-pycortex.git
 cd NHP-pycortex
 python setup.py develop
+
+# [Tip] If you're running into installation issues that are cython related: the following may help
+pip install Cython==0.29.36
+pip install scikit-learn==0.23 --no-build-isolation
+
 ```
 
+```
 Pycortex uses a configuration file to specify where things are saved. Edit it to make it point to where you want your files.
 You can check the location of the filestore after installing by running: