Update read_chn.py

Author: tegmyr

read_chn.py

@@ -11,7 +11,7 @@
 spectrum data. To be used in other source code, a general use case could be 
 getting the histogram data. The code for doing this could look like: 
 
-import read_chn3 as rc
+import read_chn as rc
 filename = <spectrum_name>.Chn
 spec_obj = rc.gamma_data(filename)
 hist_data = spec_obj.hist_array
@@ -93,4 +93,4 @@ def write_txt(self, fname):
         filename = raw_input('Filename of binary, (including .Chn): ')
     gamma_object = gamma_data(filename)
     gamma_object.write_txt(filename)
-  
+