Definition of "breaking change"

[greenled]

A while ago this project adopted Semantic Versioning (#9) and so far there are two releases out following that specification 0.1.0 and 0.1.1. As new ones are on their way, there is a need for a clear definition of what is considered a "breaking change" and what is not.

From the spec:

Software using Semantic Versioning MUST declare a public API. This API could be declared in the code itself or exist strictly in documentation. However it is done, it SHOULD be precise and comprehensive.

So, what/where is this project's public API to start with?:

• Executable's input/output format?
• Docker image definition?
• Settings?
• Algorithms (and source code in general)?
• Supported platforms?
• External dependencies?
• A mix of the above?

This issue is for addresing those questions. Findings should be added to the Readme.

[greenled]

The main use case of this tool is automating interaction with Portainer in a CI/CD pipeline (#18)