Clean up the docker file

DiscordChatExporter.Cli.dockerfile

@@ -1,5 +1,7 @@
 # -- Build
-FROM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
+# Use the same platform for the build image as the runtime image, so that it's easier
+# to produce a self-contained assembly for the right platform.
+FROM mcr.microsoft.com/dotnet/sdk:7.0-runtime AS build
 
 WORKDIR /build
 
@@ -9,6 +11,7 @@ COPY Directory.Build.props ./
 COPY DiscordChatExporter.Core ./DiscordChatExporter.Core
 COPY DiscordChatExporter.Cli ./DiscordChatExporter.Cli
 
+# Publish a self-contained assembly so we can use a slimmer runtime image
 RUN dotnet publish DiscordChatExporter.Cli \
     --self-contained \
     --use-current-runtime \
@@ -16,29 +19,27 @@ RUN dotnet publish DiscordChatExporter.Cli \
     --output ./publish
 
 # -- Run
+# Use Alpine for the runtime image due to its smaller size.
+# Use `runtime-deps` instead of `runtime` since we're running a self-contained assembly.
+# https://github.com/dotnet/dotnet-docker/blob/main/samples/selecting-tags.md
 FROM mcr.microsoft.com/dotnet/runtime-deps:7.0-alpine
 
-# Alpine dotnet image doesn't include timezone data, which is needed
-# for certain date/time operations.
+# Alpine image doesn't include timezone data, which is needed for certain date/time operations
+# https://github.com/dotnet/dotnet-docker/blob/main/samples/enable-globalization.md
 RUN apk add --no-cache tzdata
 
-# Create a non-root user to run the app, so that the output files
-# can be accessed by the host.
+# Create a non-root user to run the app, so that the output files can be accessed by the host
 # https://github.com/Tyrrrz/DiscordChatExporter/issues/851
-RUN adduser \
-    --disabled-password \
-    --no-create-home \
-    dce
-
+RUN adduser --disabled-password --no-create-home dce
 USER dce
 
 COPY --from=build /build/publish /opt/dce
 
-# Need to keep this as /out for backwards compatibility with documentation.
-# A lot of people have this directory mounted in their scripts files, so
-# changing it would break existing workflows.
+# Add the app directory to the PATH so that it's easier to run the app via `docker exec`
+ENV PATH="$PATH:/opt/dce"
+
+# This directory is exposed to the user for mounting purposes, so it's important
+# that it stays the same for backwards compatibility.
 WORKDIR /out
 
-# Add the app directory to PATH so that it's easier to debug using a shell
-ENV PATH="$PATH:/opt/dce"
 ENTRYPOINT ["DiscordChatExporter.Cli"]