Change version var name to be more clear

Author: bmonkman

Dockerfile

@@ -1,12 +1,12 @@
 FROM alpine:3.12 AS build
 
-ENV VERSION=3.1.4
+ENV SIEGE_VERSION=3.1.4
 
 RUN apk update \
     && apk add curl g++ make \
-    && curl http://download.joedog.org/siege/siege-$VERSION.tar.gz > siege-$VERSION.tar.gz \
-    && tar -xf siege-${VERSION}.tar.gz \
-    && cd siege-${VERSION} \
+    && curl http://download.joedog.org/siege/siege-${SIEGE_VERSION}.tar.gz > siege-${SIEGE_VERSION}.tar.gz \
+    && tar -xf siege-${SIEGE_VERSION}.tar.gz \
+    && cd siege-${SIEGE_VERSION} \
     && ./configure \
     && make install