add the missing date directive below slug when using Pelican

insert_date_2_rst.py

#!/usr/bin/env python3
# -*- coding: utf8 -*-

if __name__ == "__main__":
    import glob, os, datetime, fileinput
    cwd = os.getcwd()
    files = [f for f in glob.glob(cwd + os.path.sep + "**/*.rst", recursive=True)]
    for f in files:
      modifieddate = datetime.datetime.fromtimestamp(os.path.getmtime(f))
      if not ':date:' in open(f).read():
        print("%s %s" % (f, modifieddate))
        for line in fileinput.FileInput(f, inplace=1):
          if ":slug:" in line:
            line=line.replace(line,line+":date: "+modifieddate.__str__()+"\n")
          print(line, end='')