update readme

I've put an introduciton about start-notebook and how to add kernel for users with muliple Julia versions.

README.md

@@ -80,21 +80,49 @@ julia install-manual.jl
 ```
 
 ### 3) Starting the notebook
+
+#### From Julia REPL
+
 To start the notebook make sure to be in the folder `Julia-seminar` and then run `julia`: an interactive Julia command line will open. In there run this command
 
+```julia
+using Pkg
+Pkg.activate(pwd())
+using IJulia
+notebook(dir=pwd())
 ```
-using IJulia; notebook(dir=pwd())
-```
-and the notebook will automatically open in a browser.
 
+and the notebook will automatically open in a browser.
 Navigate the files and open notebook number 0.
 
+#### From command line
+
+Alternatively, one can open the notebook from the command line:
+
+```bash
+julia -L start-notebook.jl
+```
+
+### \* For users with multiple Julia versions
+
+For users with multiple Julia versions, if the corresponding kernel cannot be found in Jupyter Notebook, please run `installkernel("julia", "--project=@.")` (only once) before executing `notebook(dir=pwd())` to first install the kernel:
+
+```julia
+using Pkg
+Pkg.activate(pwd())
+using IJulia
+installkernel("julia", "--project=@.")
+notebook(dir=pwd())
+```
+
+Now, one should find a new kernel related to the current Julia version, named `julia "Julia-version"`, in Jupyter Notebook.
+
 ### Troubleshooting
 If you are facing issues, check out
 the [great troubleshooting section](https://carstenbauer.github.io/WorkshopWizard.jl/dev/troubleshooting/)
 from the WorkshopWizard package by Carsten Bauer (which is being used by `install.jl`).
 
-## For Developers: Setting Up `pre-commit`
+## For developers: setting up `pre-commit`
 
 [`pre-commit`](https://pre-commit.com/) is a framework that helps to manage and maintain pre-commit hooks to ensure that your code adheres to a consistent style, prevents errors, and adheres to other quality assurance checks.
 
@@ -107,14 +135,14 @@ from the WorkshopWizard package by Carsten Bauer (which is being used by `instal
 
    For more information and installation options, visit the [`pre-commit`](https://pre-commit.com/) website.
 
-2. **Navigate to the Project Directory:**
+2. **Navigate to the project directory:**
     Change into the project directory, i.e., `julia-seminar` by running:
 
     ```bash
     cd julia-seminar
     ```
 
-3. **Install Hooks:**
+3. **Install hooks:**
     Install the git hooks by executing:
 
     ```bash