docs: update docstrings in termsPiezo.py for sphinx
docs: update docstrings in termsPiezo.py for sphinx

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