Correct a minor grammar error. (docker#3917)

Saw a grammar correction I couldn't help but correct.

Don't run bundle update in the Dockerfile (docker#3770)

This avoids the US-ASCII bug in jekyll-redirect plugin

Merge pull request docker#2042 from londoncalling/clarify-docker-stac…

…k-deploy-voting-app

clarified docker stack deploy and bundles

UCP 2.1.0, DTR 2.2.0, CSE 1.13.1

Merge pull request docker#1184 from sanscontext/fixlink

take a stab at fixing a broken link

Docs for Datacanter: CSE 1.12.3, UCP 2.0.1, DTR 2.1.0