cloud/docker: build Upspin releases with Go 1.11

Also fix a minor documentation error.

Change-Id: I5182874ac17f396e9f59ab1e69f842dca309ce05
Reviewed-on: https://upspin-review.googlesource.com/c/19220
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/cloud/docker/cloudbuild/Dockerfile b/cloud/docker/cloudbuild/Dockerfile
index 225a431..c39aa59 100644
--- a/cloud/docker/cloudbuild/Dockerfile
+++ b/cloud/docker/cloudbuild/Dockerfile
@@ -2,6 +2,6 @@
 # builder to just build the file. (The script as part of the go builder wants
 # to do something else. Sigh.)
 
-FROM golang:1.8
+FROM golang:1.11
 ENV GOPATH /workspace
 ENTRYPOINT ["/usr/local/go/bin/go"]
diff --git a/cloud/docker/upspinserver-build/Dockerfile b/cloud/docker/upspinserver-build/Dockerfile
index 81db609..ab2d801 100644
--- a/cloud/docker/upspinserver-build/Dockerfile
+++ b/cloud/docker/upspinserver-build/Dockerfile
@@ -1,3 +1,3 @@
-FROM golang:1.9
+FROM golang:1.11
 ADD mkupspinserver.sh /mkupspinserver.sh
 ENTRYPOINT ["/mkupspinserver.sh"]
diff --git a/cloud/docker/upspinserver-build/README b/cloud/docker/upspinserver-build/README
index 924a909..d3fb50c 100644
--- a/cloud/docker/upspinserver-build/README
+++ b/cloud/docker/upspinserver-build/README
@@ -27,7 +27,7 @@
 
 Create the 'upspinserver' build step using upspin-deploy-gcp:
 	$ go get gcp.upspin.io/cmd/upspin-deploy-gcp
-	$ upspin-deploy-gcp -release-image
+	$ upspin-deploy-gcp -upspinserver-image
 
 Create a trigger that runs the relevant build steps
 on each new commit to the 'gcp':