Output yml/yaml as text/plain through nginX in docker container

[ghost]

Description

Added type text/plain for yml and yaml in docker/nginx.conf.

Motivation and Context

Ref #6019 (not sure if this covers all the problems mentioned there). When you did specify a *.y(a)ml file for the configUrl this was not working with the provided docker image. The reason seems to be that the bundled nginX has no MIME type entry for YAML and so outputs this as application/octet-stream. That caused the config not to load. Adding text/plain types for *.y(a)ml seems to have fixed the problem.

How Has This Been Tested?

Build a docker image locally and tested if it worked with the provided swagger-config.yaml file.

Screenshots (if appropriate):

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[tim-lai]

@glamic-ep PR merged! Thanks for help with nginx!