What was the class when adt champion racing ranked 1st with an audi r8 chassis, and less than 206 points?
CREATE TABLE "complete_american_le_mans_series_results" (
  "year" real,
  "entrant" text,
  "class" text,
  "chassis" text,
  "engine" text,
  "tyres" text,
  "rank" text,
  "points" real
);
SELECT "class" FROM "complete_american_le_mans_series_results" WHERE "points"<206 AND "chassis"='audi r8' AND "entrant"='adt champion racing' AND "rank"='1st';