fix Approximation.describe_geometry(), update docstring
fix Approximation.describe_geometry(), update docstring

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