Update installation_user.md

The error 'OSKAR library not found' seems to become a frequent issue. I moved the troubleshooting for this issue up closer to the installation instructions.

doc/src/installation_user.md

@@ -27,9 +27,10 @@ conda install -c nvidia/label/cuda-11.7.0 -c i4ds -c conda-forge karabo-pipeline
 conda env config vars set LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/wsl/lib
 ```
 
-Karabo versions older than `v0.15.0` are deprecated and therefore installation will most likely fail. In addition, we do not support Karabo older than latest-minor version in case dependency resolving or online resources are outdated. Therefore, we strongly recommend using the latest version of Karabo. If an older version of Karabo is required, we recommend using a [container](container.md), as the environment is fixed in a container, or extract the environment dependencies using `conda env export --no-builds`. However, outdated online resources may still occur.
+## Dealing with the error 'OSKAR library not found'
+If you use Karabo and get the error `RuntimeError: OSKAR library not found.` then this because the correct CUDA drivers are not installed. More information about this issue can be found [here (issue #568)](https://github.com/i4Ds/Karabo-Pipeline/issues/568). Refer to this issue for a workaround.
 
-Please refer to the troubleshooting section at the bottom of this page if you feel something does not work.
+Please refer to the troubleshooting section at the bottom of this page if you feel something else does not work.
 
 ## Update to latest Karabo version
 A Karabo installation can be updated the following way:
@@ -40,7 +41,10 @@ Note: Even though we care about not introducing API-breaking changes through dif
 conda update -c nvidia/label/cuda-11.7.0 -c i4ds -c conda-forge karabo-pipeline
 ```
 
-## Additional Notes and Troubleshooting
+## Older versions of Karabo
+Karabo versions older than `v0.15.0` are deprecated and therefore installation will most likely fail. In addition, we do not support Karabo older than latest-minor version in case dependency resolving or online resources are outdated. Therefore, we strongly recommend using the latest version of Karabo. If an older version of Karabo is required, we recommend using a [container](container.md), as the environment is fixed in a container, or extract the environment dependencies using `conda env export --no-builds`. However, outdated online resources may still occur.
+
+
+## Additional notes and troubleshooting
 - Don't install anything into the base environment except libraries which are supposed to live in there. If you accidentally install packages there which are not supposed to be there, you might break some functionalities of your conda-installation.
 - If you're using a system conda, it might be that you don't have access to a libmamba-solver, because the solver lives in the base environment, which belongs to root. In this case, you can ask your admin to install the solver, try an installation without the libmamba solver OR we recommend to just install conda into your home (which is the recommended solution).
-- In some rare cases the correct CUDA drivers are not installed. This may be the case when you get the error `RuntimeError: OSKAR library not found.` More information about this issue can be found [here (issue #568)](https://github.com/i4Ds/Karabo-Pipeline/issues/568). Refer to this issue for a workaround.