because of:

Step 5/20 : RUN go get -d -v github.com/slimhazard/gogitversion &&     cd /go/src/github.com/slimhazard/gogitversion &&     make install
 ---> Running in 8a50294f4b5c
github.com/slimhazard/gogitversion (download)
godoc -html . | pandoc -f html -t markdown_github > README.md
/bin/sh: 1: pandoc: not found
/bin/sh: 1: godoc: not found
make: *** [Makefile:36: README.md] Error 127