Clean up dockerfile and add comments

Dockerfile

@@ -1,14 +1,16 @@
+# Use alpine linux as base image.
 FROM alpine:3.20
 
-# Install dependencies
+# Install mumble-server.
 RUN apk add --no-cache \
-        bash \
-        curl \
-        murmur
+        murmur \
+        curl
 
+# Create mumble user and group environment variables.
 ARG MUMBLE_UID=1000
 ARG MUMBLE_GID=1000
 
+# Create mumble user and group.
 RUN addgroup \
         --gid $MUMBLE_GID \
         mumble && \
@@ -19,15 +21,22 @@ RUN addgroup \
         --ingroup mumble \
         mumble
 
+# Set the mumble-server configuration directory owner.
 RUN mkdir -p /config && \
     chown -R mumble:mumble /config
 
+# Set the mumble-server configuration directory
+# as the working directory with mumbe user.
 USER mumble
 WORKDIR /config
+
+# Expose mumble-server ports.
 EXPOSE 64738/tcp 64738/udp
+
+# Copy entrypoint script.
 COPY entrypoint.sh /entrypoint.sh
 
-# Start mumble-server
+# Start mumble-server.
 VOLUME ["/config"]
 ENTRYPOINT ["/entrypoint.sh"]
 CMD ["/usr/bin/mumble-server", "-fg"]