docs: small fixes in Primer
docs: small fixes in Primer

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