Update Dockerfile

Updated comments.

Dockerfile

@@ -1,4 +1,5 @@
 # The base image. 
+# FROM eclipse-temurin:21-jdk-jammy as builder
 FROM eclipse-temurin:21-jdk-alpine
 
 # The work directory. 
@@ -8,14 +9,17 @@ WORKDIR /
 ENV PORT=9090
 EXPOSE $PORT
 
+# Copy the source code into the Docker image.
+# Docker uses caching to speed up builds by reusing layers from previous builds. 
+# To take advantage of caching, you should order your Dockerfile instructions so that the ones that change frequently are placed towards the end of the file. 
+# For example, if you’re copying files into the image, you should do that at the end of the Dockerfile.
 # The JAR file path. 
 # ARG JAR_FILE=*.jar
 # ARG JAR_FILE=the-review-room-0.0.1-SNAPSHOT.jar
 
 # Copy the JAR file from the build context into the Docker image. 
 # COPY target/${JAR_FILE} application.jar
 
-# Copy the source code into the Docker image.
 COPY .mvn/ .mvn
 COPY mvnw pom.xml ./
 
@@ -24,11 +28,19 @@ COPY src ./src
 # Modify the permissions of the mvnw script. 
 RUN chmod +x ./mvnw
 
-# CMD apk update \
-#     && rm -rf /var/cache/apk/*
+# RUN apk add --no-cache \
+#         package1 \
+#         package2 \
+#         package3 && \
+#     rm -rf /var/cache/apk/* /tmp/*
+
+# RUN apt-get update && \
+#     rm -rf /var/lib/apt/lists/*
+
+# RUN apt-get update && \
+#     apt-get install -y postgresql postgresql-contrib && \
+#     rm -rf /var/lib/apt/lists/*
 
-# Set the default command to run the Java application. 
-#ENTRYPOINT ["java", "-Xmx2048M", "-jar", "/application.jar"]
-# ENTRYPOINT ["java","-jar","/application.jar"]
+# Compile the Java application.
 RUN ./mvnw install -DskipTests
 CMD ["./mvnw", "spring-boot:run"]