As far as I see it, there is none. However, it's a so basic functionality, it doesn't really need an explanation beyond the configuration user interface you see with Tools->Automatic Scene Switcher.
The core principle is:
- Permanently look for the foreground app: if one of the configured window titles match the current foreground app, switch to the assigned scene
- if none of the configured window titles match the current foreground app, switch to the scene given bei "Switch To" or none, if "Don't switch"
You might need help with how to add match rules. The drop down list presents a list of all current window titles. Choose one from the drop down or click into the field and input the title yourself, if some app isn't active this moment. Then choose the corresponding scene on the right and click the + to add the rule to OBS.
You don't need to enter a full window title. You can enter a short but identifying text. For example, OBS sees the title of Google Chrome while I type this message as "Using Automatic Scene Switcher | OBS Forums - Google Chrome". To enter a rule to make OBS switch so a certain scene while I browse the OBS forums regardless the topic, I will just enter the partial string "OBS Forums - Google Chrome" as rule.