[add] docker instructions, [add] metadata gathering, [add] screenshots

Dockerfile

@@ -1,19 +1,35 @@
-FROM alpine:edge AS build
-RUN apk add --no-cache --update go gcc g++
-WORKDIR /app
-COPY . /app
+# Certificate Store
+FROM alpine as certs
+RUN apk update && apk add ca-certificates
 
-# Copy Resources
+# Build Image
+FROM --platform=$BUILDPLATFORM golang:1.20 AS build
+
+# Install Dependencies
+RUN apt-get update -y
+RUN apt install -y gcc-x86-64-linux-gnu
+
+# Create Package Directory
+WORKDIR /src
 RUN mkdir -p /opt/bookmanager
-RUN cp -a ./templates /opt/bookmanager/templates
-RUN cp -a ./assets /opt/bookmanager/assets
 
-# Download Dependencies & Compile
-RUN go mod download
-RUN CGO_ENABLED=1 CGO_CFLAGS="-D_LARGEFILE64_SOURCE" go build -o /opt/bookmanager/server
+# Cache Dependencies & Compile
+ARG TARGETOS
+ARG TARGETARCH
+RUN --mount=target=. \
+    --mount=type=cache,target=/root/.cache/go-build \
+    --mount=type=cache,target=/go/pkg \
+    if [ "$TARGETARCH" = "amd64" ]; then \
+	GOOS=$TARGETOS GOARCH=$TARGETARCH CGO_ENABLED=1 CGO_CFLAGS="-D_LARGEFILE64_SOURCE" CC=x86_64-linux-gnu-gcc go build -o /opt/bookmanager/server; \
+    else \
+	GOOS=$TARGETOS GOARCH=$TARGETARCH CGO_ENABLED=1 CGO_CFLAGS="-D_LARGEFILE64_SOURCE" go build -o /opt/bookmanager/server; \
+    fi; \
+    cp -a ./templates /opt/bookmanager/templates; \
+    cp -a ./assets /opt/bookmanager/assets;
 
 # Create Image
-FROM alpine:3.18
+FROM busybox:1.36
+COPY --from=certs /etc/ssl/certs /etc/ssl/certs
 COPY --from=build /opt/bookmanager /opt/bookmanager
 WORKDIR /opt/bookmanager
 EXPOSE 8585