docs: add multi-linear terms section to developer guide (WIP)
docs: add multi-linear terms section to developer guide (WIP)

vlukes/sfepy,vlukes/sfepy,rc/sfepy,vlukes/sfepy,BubuLK/sfepy,sfepy/sfepy,rc/sfepy,rc/sfepy,sfepy/sfepy,sfepy/sfepy,BubuLK/sfepy,BubuLK/sfepy