Co-authored-by: Renovate Bot <bot@renovateapp.com>

* add no-cache option for smaller images

* move flag immediately after `apk`

adjusting to be as close to the example as possible: https://github.com/gliderlabs/docker-alpine/blob/master/docs/usage.md#disabling-cache

* add `onFound` callback to schemas
* add warning to method docs (for #4957)
* implement Docker OAuth2 init block support
* update docs
* add OAUTH_SCOPE_SEPARATOR
* drop OAuth env from Dockerfile and run script
* don't indent the first oauth block line
* drop unused `dedent` import
* touch up warning message
* add more test cases
* return an empty block if no OAuth content is generated
* fix broken doc line

* reorganize docker things

* Configurator WIP

* implement Docker runtime config generator

* add tests

* update documentation

* fix Markdown tables

* Move Docker section

* add note to README

* move up `nodejs` install for more aggressive caching

* drop exclusive test

* fix missing `DISPLAY_OPERATION_ID`

Closes #4861

The nginx image contains a newer viersion on nginx

* [Dockerfile] Use `--no-cache` instead of `--update` for `apk add`
  To prevent unnecessary cache in the Docker image.
* [Dockerfile] Use `COPY` instead of `ADD` for non tarball file copying
* [Dockerfile] Update base image from Alpine v3.5 to v3.8

The API_URLS environment variable can be used to run the Docker image with multiple urls.

Example:
docker run -p 80:8080 -e API_URLS=[{name:"First API", url:"http://firstapiurl"},{name:"Second API", url:"http://secondapiurl"}] swaggerapi/swagger-ui

* Use PORT to override nginx listen port when defined
* Add dockerignore to make build context smaller

- reverted to port 8080 for the docker image

- removed node dependency
- removed un-necessary source-code bulk

- serving just the static content

- simplified Dockerfile definition
- explicitly exposed the port