Fix velocity magnitude title

Author: xylar

mpas_analysis/default.cfg

@@ -2202,7 +2202,7 @@ availableVariables = {
          'units': r'm s$$^{-1}$$',
          'mpas': ['timeMonthly_avg_velocityMeridional']},
     'velocityMagnitude':
-        {'title': 'Zonal Velocity',
+        {'title': 'Velocity Magnitude',
          'units': r'm s$$^{-1}$$',
          'mpas': ['timeMonthly_avg_velocityZonal',
                   'timeMonthly_avg_velocityMeridional']},