add PESPlib link to Liebchen submission (closes #11)

4c58695a-420f-4fc9-bcd6-b3eff2bc3cc8/meta.yml

 company: Technische Hochschule Wildau
 creator: Christian Liebchen
 description: "Periodic Event Scheduling Problem (PESP) Model for Timetable Optimization\
-  \ in Public Transport\r\nData originating from (see additional file) https://lintim.math.uni-goettingen.de/\r\
+  \ in Public Transport\r\nData originating from (see additional file) http://num.math.uni-goettingen.de/~m.goerigk/pesplib/\r\
   \nNotation of the variables in the MIP model according to Sec. 9 in Liebchen (2006)"
 email: liebchen@th-wildau.de
 license: cc-license