message: js(doc): fix path
diff: @@ -287,20 +287,20 @@ So, make sure [docker](https://www.docker.com/) is installed in your system and
  @code{.bash}
  git clone https://github.com/opencv/opencv.git
  cd opencv
  -docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk emcmake python3 ./dev/platforms/js/build_js.py build_js
  +docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk emcmake python3 ./platforms/js/build_js.py build_js
  @endcode
  In Windows use the following PowerShell command:
  @code{.bash}
  -docker run --rm --workdir /src -v "$(get-location):/src" "emscripten/emsdk" emcmake python3 ./dev/platforms/js/build_js.py build_js
  +docker run --rm --workdir /src -v "$(get-location):/src" "emscripten/emsdk" emcmake python3 ./platforms/js/build_js.py build_js
  @endcode
  @warning
  The example uses latest version of emscripten. If the build fails you should try a version that is known to work fine which is `2.0.10` using the following command:
  @code{.bash}
  -docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk:2.0.10 emcmake python3 ./dev/platforms/js/build_js.py build_js
  +docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk:2.0.10 emcmake python3 ./platforms/js/build_js.py build_js
  @endcode
  ### Building the documentation with Docker
  @@ -324,5 +324,5 @@ docker build . -t opencv-js-doc
  Now run the build command again, this time using the new image and passing `--build_doc`:
  @code{.bash}
  -docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) "opencv-js-doc" emcmake python3 ./dev/platforms/js/build_js.py build_js --build_doc
  +docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) "opencv-js-doc" emcmake python3 ./platforms/js/build_js.py build_js --build_doc
  @endcode
  