Tap or swipe left/right/up/down on your clock face to launch up to five apps of your choice. The extension (included) can be chosen as one of the apps, in turn providing fast access to up to five additional apps per extension screen - which can be stacked indefinitely. Configurations can be accessed through Settings->Apps.
With the introduction of stackable extension screens in v0.12 of Quick Launch the keys of the settings file have been changed. Please just visit Settings->Apps->Quick Launch to prompt an automatic update. Quick Launch will not be responsive until this has been done.