Add nnpfc_absent_input_pic_zero_flag to software-manual.tex

doc/software-manual.tex

@@ -5989,6 +5989,10 @@ Specifies sii_num_units_in_shutter_interval for single entry.If multiple entries
   \Default{false} &
   Indicates whether the i-th neural network post filter generates a corresponding output picture for the i-th input picture. 
   \\
+  \Option{SEINNPFCAbsentInputPicZeroFlag\emph{i}} &
+  \Default{false} &
+  Specifies the nnpfc_absent_input_pic_zero_flag of the \emph{i}-th neural network post-filter.
+  \\
 \end{OptionTableNoShorthand}
 
 \begin{OptionTableNoShorthand}{Neural network post-filter activation}{tab:sei-nn-post-filter-activation}