Flip update-description default value.

This allows for backwards-compatibility - also updated associated
example.

Merge pull request CircleCI-Public#47 from ArmaanT/feature/dockerhub-…

…descriptions

Add update description command

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.20

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.20`

Merge pull request CircleCI-Public#45 from CircleCI-Public/add-dlc-do…

…cker-example

Add DLC to Docker executor example

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.19

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.19`

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.18

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.18`

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.17

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.17`

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.16

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.16`

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.15

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.15`

patch

View this orb release in the orb registry:

https://circleci.com/orbs/registry/orb/circleci/docker?version=0.5.14

View this orb release using the CircleCI CLI:

`circleci orb source circleci/docker@0.5.14`