Create polish_for_humanities.csl

This is a standard Polish style in humanities. It's available online but not in via repositiory, which makes it difficult to use:

http://www.doktoranci.uj.edu.pl/start/-/blogs/polski-styl-cytowan-w-programie-mendeley?_33_redirect=http%3A%2F%2Fwww.doktoranci.uj.edu.pl%2Fstart%3Fp_p_id%3D33%26p_p_lifecycle%3D0%26p_p_state%3Dnormal%26p_p_mode%3Dview%26p_p_col_id%3Dcolumn-2%26p_p_col_count%3D1%26_33_struts_action%3D%252Fblogs%252Fview
remove ```form="numeric"``` that doesn't exist for years.