Cleaned up and adjusted the Docker build environment

Dockerfile

@@ -1,4 +1,4 @@
-FROM fedora:latest
+FROM fedora:36
 
 RUN dnf install -y  \
     gcc-c++ \

README.md

@@ -155,15 +155,22 @@ Note that the code uses `strlcpy()` also in the test code, which requires `libbs
 
 ### Building the firmware with Docker
 
-Building with Docker can help address issues with the build process on some platforms, including the `strlcpy()` errors observed on certain Linux distributions.
+Using Docker to build the firmware is usually the easiest option, because it provides a stable Fedora Linux-based
+build environment on any platform. It should work on Windows and Mac operating systems too.
+
+The Docker environment can also help address issues with the build process, including the `strlcpy()` errors observed on certain Linux distributions.
 
 1. Install Docker if not already installed
-2. Build the firmware using the following commands
+2. Set the current directory to the RS41ng source directory
+3. Build the RS41ng compiler Docker image using the following command. It is necessary to build the Docker image only once.
     ```
     docker build -t rs41ng_compiler .
-    docker run --rm -it -v $(pwd):/usr/src/rs41ng rs41ng_compiler
     ```
-3. The firmware will be stored in this directory.
+4. Build the firmware using the following command. If you need to rebuild the firmware, simply run the command again.
+    ```
+    docker run --rm -it -v $(pwd):/usr/local/src/RS41ng rs41ng_compiler
+    ```
+5. The firmware will be stored in file `build/src/RS41ng.elf`
 
 ## Flashing the firmware
 

docker_build.sh

@@ -1,22 +1,26 @@
-# Script to compile RS41ng on any platform
-# This script is copied into the docker image when it is built, if you plan to change this script, please make sure to rebuild the docker image
+#!/bin/bash
+
+# Script to compile RS41ng on any platform using Docker
+# This script is copied into the Docker image when it is built.
+# If you plan to change this script, please make sure to rebuild the Docker image.
+
 set -e # Exit if failed
 
+SOURCE_PATH="/usr/local/src/RS41ng"
+
 # Sanity check
-if [ ! -d "/usr/src/rs41ng" ]
+if [ ! -d "${SOURCE_PATH}" ]
 then
-    echo "Build directory does not exist, please run the command given in README to mount the source directory"
+    echo "Source directory does not exist, please run the Docker command given in README to mount the source directory"
     exit 1
 fi
 
 # Build RS41ng
-cd /tmp/
-mkdir rs41ng_build && cd rs41ng_build
-cmake /usr/src/rs41ng
+cd "${SOURCE_PATH}"
+rm -rf build
+mkdir -p build
+cd build
+cmake ..
 make -j$(nproc)
-# Copy the binary, ELF and hex to the home directory
-cp src/RS41ng.elf /usr/src/rs41ng
-cp RS41ng.hex /usr/src/rs41ng
-cp RS41ng.bin /usr/src/rs41ng
 
 echo "RS41ng build complete"