docs: add information on what to do when the execution policy prevents the script from being executed

README.md

@@ -37,3 +37,9 @@ You can do the same as for Linux. If you do not want to use the terminal at all:
 
 1. Download the `install.ps1` script to the location where you want the Optolith database to be installed.
 2. Right-click on the script file in Windows Explorer and select *Run with PowerShell* from the context menu.
+
+If PowerShell displays an error about something like that the script is not signed and that the execution policy does not permit running the script, you will actually have to run PowerShell itself once. `Shift+Rightclick` in the folder where you downloaded the `install.ps1` in the Windows Explorer and select *Open PowerShell here*. Then, copy the following command, paste it into PowerShell and hit `Enter`.
+
+```sh
+powershell -executionpolicy bypass -File .\install.ps1
+```