pass dummy user/group 1000 on windows host

Dockerfile

@@ -14,8 +14,7 @@ RUN pip install pyyaml
 RUN addgroup --gid $GROUP_ID inav; exit 0;
 RUN adduser --disabled-password --gecos '' --uid $USER_ID --gid $GROUP_ID inav; exit 0;
 
-ARG INAV_IMAGE_USER=inav
-USER $INAV_IMAGE_USER
+USER inav
 
 RUN git config --global --add safe.directory /src
 

docs/development/Building in Docker.md

@@ -33,9 +33,8 @@ If you are getting error "standard_init_linux.go:219: exec user process caused:
 
 You'll have to manually execute the same steps that the build script does:
 
-1. `docker build --build-arg INAV_IMAGE_USER=root -t inav-build .`
+1. `docker build --build-arg USER_ID=1000 --build-arg GROUP_ID=1000 -t inav-build .`
    + This step is only needed the first time.
-   + Note that on Windows/WSL 2 mounted /src folder is writeable for root user only. You have to run build under root user. This is achieved with `--build-arg INAV_IMAGE_USER=root` option in the command line above.   
    + If GDB should be installed in the image, add argument '--build-arg GDB=yes'
 2. `docker run --rm -it -v <PATH_TO_REPO>:/src inav-build <TARGET>`
    + Where `<PATH_TO_REPO>` must be replaced with the absolute path of where you cloned this repo (see above), and `<TARGET>` with the name of the target that you want to build.