Updates species dictionary path for RMG

Updates the species dictionary path to "dictionary.txt" to align with the expected file name for RMG kinetics libraries, whereas thermo uses "species_dictionary.txt".

It appears that RMG, since 3.9, prefers it to be called dictionary.txt

Removes redundant comments

Removes comments that state the expected file name for species dictionaries in kinetics libraries.
This information is either redundant or outdated.

Author: calvinp0

arc/plotter.py

@@ -905,7 +905,7 @@ def save_kinetics_lib(rxn_list: list,
     with open(reactions_file, 'w') as f:
         f.write(reactions_txt)
 
-    species_dict_path = os.path.join(lib_path, 'species_dictionary.txt')
+    species_dict_path = os.path.join(lib_path, 'dictionary.txt')
     with open(species_dict_path, 'w') as f:
         for label, adjlist in species_dict.items():
             f.write(f'{label}\n{adjlist}\n')