Added link to one_pfb.m Matlab model.

libraries/dsp/verify_pfb/tb_verify_pfb_response.vhd

@@ -28,7 +28,8 @@
 --     device under test (DUT).
 --   . The FIR coefficients are flipped per tap, so per set of N_fft = 1024 values. This is
 --     because the FIR coefficients are applied as a filter per FFT input (so using
---     convolution), and not as a window function (using plain multiply).
+--     convolution). For more clarification see
+--     https://git.astron.nl/desp/apertif_matlab/-/blob/master/matlab/one_pfb.m
 --
 -- Usage:
 --   > as 3 default, or as 12 for details