Deletion of Sulisław of Cracow

Comment: Sources now on the page are reliable.  I searched   Sulisław + Legnica and can see a fair number of sources in Polish, books and scholarly articles both.  He was, moreover the brother of a Voivode (ducal or princely rank and ruler of a territory) and his son succeeded to that throne.  Meet  #4 and #5
Stance: keep
Cited policy: Wikipedia:Notability (WP:SOLDIER)