Use just groff-base in s2i-core

Dockerfile

@@ -1,5 +1,5 @@
 # This image is the base image for all s2i configurable container images.
-FROM registry.fedoraproject.org/fedora:27
+FROM registry.fedoraproject.org/fedora:28
 
 ENV SUMMARY="Base image which allows using of source-to-image."	\
     DESCRIPTION="The s2i-core image provides any images layered on top of it \
@@ -7,7 +7,7 @@ with all the tools needed to use source-to-image functionality while keeping \
 the image size as small as possible." \
     NAME=s2i-core \
     VERSION=0 \
-    RELEASE=7 \
+    RELEASE=8 \
     ARCH=x86_64
 
 LABEL summary="$SUMMARY" \
@@ -42,7 +42,7 @@ ENV \
 RUN INSTALL_PKGS="bsdtar \
   findutils \
   gettext \
-  groff \
+  groff-base \
   tar \
   unzip" && \
   mkdir -p ${HOME}/.pki/nssdb && \