theme: upgrade to latest v4.1 dev (talk front matter upgraded)

Also:

- Project and Custom widgets renamed (upgraded)
- Rearranges section positions and adds demo section to introduce
the template and help the user get started

config/_default/params.toml

@@ -56,11 +56,10 @@ address = "Building 1 Room 1, Stanford University, California, 90210, USA"
 
 # Office hours: use `<br>` to insert a line break, or set to "" to remove office hours
 office_hours = """Monday 10:00 to 13:00<br>
-                  Wednesday 09:00 to 10:00<br>
-                  Otherwise email to book an appointment"""
+                  Wednesday 09:00 to 10:00"""
 
 # Enter an optional link for booking appointments (e.g. calendly.com).
-appointment_url = ""
+appointment_url = "https://calendly.com"
 
 # Contact links
 #   Set to `[]` to disable, or comment out unwanted lines with a hash `#`.