BRAVO say critics about an entertainers tell-all memoir chronicling her days in the cabaret act Barry Nichols and Les Girls. Libel! Cries another of Les Girls, setting in motion a talons- and fact-baring litigation that proves Les Girls will be girls and that Cole Porter movie musicals will always sparkle. Gene Kelly plays Nichols, and Mitzi Gaynor, Golden Globe Best Actress winner Kay Kendall and Taina Elg are the femmes in this George Cukor-directed romp that won a Best Costume Design Oscar * and another Golden Globe for Best Comedy/Musical. Among the highlights: a ribald Ladies in Waiting and a hepcat parody of The Wild One called Why Am I So Gone About That Gal? You'll be so gone about Les Girls.