Update readme.

See https://github.com/google/guetzli/issues/146#issuecomment-290022456 for where this fix is coming from. It's a bit of a hack but it will do for now.

Dockerfile

@@ -6,35 +6,23 @@ FROM alpine:3.5
 #		libpng
 
 # Dev & build
-ARG GFLAGS_VERSION=v2.2.0
-ARG GUETZLI_VERSION=v1.0
+ARG GUETZLI_VERSION=v1.0.1
 RUN \
 	apk add --no-cache --virtual .build-deps \
-		libpng-dev \
 		alpine-sdk \
-		git \
-		coreutils \
 		cmake \
+		coreutils \
+		git \
+		libpng-dev \
+		zlib-dev \
 		&&\
-\
-	git clone "https://github.com/gflags/gflags.git" /var/tmp/gflags &&\
-	(cd /var/tmp/gflags &&\
-		git checkout "${GFLAGS_VERSION}" &&\
-		mkdir build &&\
-		cd build &&\
-		cmake .. &&\
-		make -j$(nproc) all install DESTDIR="/opt/build" \
-	) &&\
 \
 	git clone "https://github.com/google/guetzli.git" /var/tmp/guetzli &&\
 	(cd /var/tmp/guetzli &&\
 		git checkout "${GUETZLI_VERSION}" &&\
 		make -j$(nproc) config=release \
 			TARGETDIR=/usr/local/bin \
-			LDFLAGS="-L/opt/build/usr/local/lib -static" \
-			CXXFLAGS="-I/opt/build/usr/local/include" \
-			CFLAGS="-I/opt/build/usr/local/include" \
-			CPPFLAGS="-I/opt/build/usr/local/include" \
+			LDFLAGS="-static -lpng -lz -lm" \
 	) &&\
 \
 	apk del --no-cache .build-deps &&\

README.md

@@ -7,7 +7,7 @@ so it is possible to use `docker run` on this image just as if you would use gue
 
 All available tags are always listed [in Docker Hub](https://hub.docker.com/r/icedream/guetzli/tags), the list below explains the maintained tags:
 
-- `latest`, `1`, `1.0`: Latest stable version.
+- `latest`, `1`, `1.0.1`: Latest stable version.
 
 ## Examples