fix(dockerfile): improve documentation and change working directory (#4)

- Installs code at /home/speckle to prevent collisions with files & directories in the root (/) directory
- Updates the README and provides instructions for building and testing the docker image locally
- Updated inline documentation in Dockerfile

Dockerfile

@@ -1,6 +1,16 @@
+# We use the official Python 3.11 image as our base image and will add our code to it. For more details, see https://hub.docker.com/_/python
 FROM python:3.11-slim
 
+# We install poetry to generate a list of dependencies which will be required by our application
 RUN pip install poetry
 
-COPY . .
-RUN poetry export -f requirements.txt --output requirements.txt && pip install -r requirements.txt
+# We set the working directory to be the /home/speckle directory; all of our files will be copied here.
+WORKDIR /home/speckle
+
+# Copy all of our code and assets from the local directory into the /home/speckle directory of the container.
+# We also ensure that the user 'speckle' owns these files, so it can access them
+# This assumes that the Dockerfile is in the same directory as the rest of the code
+COPY . /home/speckle
+
+# Using poetry, we generate a list of requirements, save them to requirements.txt, and then use pip to install them
+RUN poetry export --format requirements.txt --output /home/speckle/requirements.txt && pip install --requirement /home/speckle/requirements.txt