include: add sve2 to documentation of SDL_HINT_CPU_FEATURE_MASK

include/SDL3/SDL_hints.h

@@ -675,6 +675,7 @@ extern "C" {
  * - "avx512f"
  * - "arm-simd"
  * - "neon"
+ * - "sve2"
  * - "lsx"
  * - "lasx"
  *