MAINT: fix broken link

pysatNASA/instruments/cnofs_vefi.py

@@ -23,9 +23,10 @@
 spacecraft is to enable an accurate V x B measurement along the spacecraft
 trajectory.  In order to provide an in-flight calibration of the magnetic field
 data, we compare the most recent POMME model (the POtsdam Magnetic Model of the
-Earth, https://geomag.us/models/pomme5.html) with the actual magnetometer
-measurements to help determine a set of calibration parameters for the gains,
-offsets, and non-orthogonality matrix of the sensor axes.  The calibrated
+Earth, https://geomag.colorado.edu/pomme-5-magnetic-model-of-the-earth.html)
+with the actual magnetometer measurements to help determine a set of calibration
+parameters for the gains, offsets, and non-orthogonality matrix of the sensor
+axes.  The calibrated
 magnetic field measurements are provided in the data file here. The VEFI
 magnetic field data file currently contains the following variables:
 B_north   Magnetic field in the north direction