faq entry to configure a default launchdir for a worker

In some cases one might want to set a default launchdir to organize all launches from a worker, instead of having launcher folders (launcher_YYYY-DD-MM-HH-mm-NN) in several directories spread through one's system. Centralizing launch folders in one place can be useful, for example, for organizing outputs from specific projects. The default launchdir is briefly mentioned here. However, a more detailed recipe to configure the default launchdir using the Python API could be added as an entry to the FAQs section.