message: 3rdparty: Update readme.txt for libjpeg-turbo simd
diff: @@ -20,6 +20,7 @@ libjpeg-turbo libjpeg-turbo is covered by three compatible BSD-style ope
  WITH_JPEG CMake option must be ON to add libjpeg or libjpeg-turbo support to imgcodecs.
  BUILD_JPEG=ON selects libjpeg-turbo by default (since OpenCV 3.4.2).
  Enable BUILD_JPEG_TURBO_DISABLE=ON to force using of libjpeg (this option is removed in OpenCV 4.0).
  + SIMD instructions are enabled by default. Use ENABLE_LIBJPEG_TURBO_SIMD to control SIMD instructions.
  ------------------------------------------------------------------------------------
  libpng Portable Network Graphics library.
  The license and copyright notes can be found in libpng/LICENSE.
  