Fixed build instructions

Author: nicholasdille

tools/docker-manpages/Dockerfile.template

@@ -20,9 +20,7 @@ RUN git clone -q --config advice.detachedHead=false --depth 1 --branch "v${versi
 ENV GO111MODULE=auto \
     DISABLE_WARN_OUTSIDE_CONTAINER=1 \
     GOPATH=/go
-RUN sed -i -E 's|^(\s+)(log.Printf\("WARN:)|\1//\2|' man/generate.go \
- && sed -i -E 's|^(\s+)"log"||' man/generate.go \
- && make manpages
+RUN make manpages
 RUN cp -r man/man1 "${prefix}${target}/share/man/" \
  && cp -r man/man5 "${prefix}${target}/share/man/" \
  && cp -r man/man8 "${prefix}${target}/share/man/"