add doc

matlab/tfgm/utils/plot_win.m

 function plot_win(win, fs, sig_len, win_type)
 %% plot_win(win, fs, sig_len, win_type)
-% This function displays the analysis window
+% Plot window
 %
 % Inputs:
-%      - win : analysis window
-%      - fs : sampling frequency
-%      - sig_len :  signal lenght
-%      - win_type: window type (str)
+%      - win (nd array): analysis window
+%      - fs (int): sampling frequency
+%      - sig_len (int):  signal length
+%      - win_type (str): window type
 %
 % Author: Marina KREME
 %%