gen_gallery.py: include docstrings of examples
gen_gallery.py: include docstrings of examples

- update generate_rst_files()

RexFuzzle/sfepy,rc/sfepy,vlukes/sfepy,lokik/sfepy,lokik/sfepy,lokik/sfepy,rc/sfepy,sfepy/sfepy,rc/sfepy,vlukes/sfepy,vlukes/sfepy,lokik/sfepy,BubuLK/sfepy,sfepy/sfepy,RexFuzzle/sfepy,BubuLK/sfepy,BubuLK/sfepy,RexFuzzle/sfepy,sfepy/sfepy,RexFuzzle/sfepy