Update Dockerfile

Added fix for DockerFile as pointed out by attiladoor

Dockerfile

@@ -1,12 +1,12 @@
-#
 # Dockerfile for cpuminer-opt
 # usage: docker build -t cpuminer-opt:latest .
 # run: docker run -it --rm cpuminer-opt:latest [ARGS]
 # ex: docker run -it --rm cpuminer-opt:latest -a cryptonight -o cryptonight.eu.nicehash.com:3355 -u 1MiningDW2GKzf4VQfmp4q2XoUvR6iy6PD.worker1 -p x -t 3
-#
-
+# for enabling huge pages, add --privileged flag
+# for enabling MSR add additonal --cap-add=ALL -v /lib/modules:/lib/modules flags (only on linux host)
+# Contributed by attiladoor
 # Build
-FROM ubuntu:16.04 as builder
+FROM ubuntu:20.04 as builder
 
 RUN apt-get update \
   && apt-get install -y \
@@ -16,18 +16,21 @@ RUN apt-get update \
     libcurl4-openssl-dev \
     libjansson-dev \
     automake \
+    zlib1g-dev \
   && rm -rf /var/lib/apt/lists/*
 
 COPY . /app/
 RUN cd /app/ && ./build.sh
 
-# App
-FROM ubuntu:16.04
+#App
+FROM ubuntu:20.04
 
 RUN apt-get update \
   && apt-get install -y \
-    libcurl3 \
+    libcurl4 \
     libjansson4 \
+    kmod \
+    msr-tools \
   && rm -rf /var/lib/apt/lists/*
 
 COPY --from=builder /app/cpuminer .