Add P option to wave_type in config file

sourcespec/configspec.conf

@@ -115,11 +115,11 @@ win_length = float(default=5.0)
 
 
 # SPECTRUM PARAMETERS --------
-# Wave type to analyse: 'S', 'SH' or 'SV'
+# Wave type to analyse: 'P', 'S', 'SH' or 'SV'
 # If 'SH' or 'SV' are selected, traces are rotated in the radial-transverse
 # system. Transverse component is used for 'SH', radial (and vertical)
 # components are used for 'SV'
-wave_type = option('S', 'SH', 'SV', default='S')
+wave_type = option('P', 'S', 'SH', 'SV', default='S')
 
 # Integrate in time domain (default: integration in spectral domain)
 time_domain_int = boolean(default=False)