Fix reference to the OpenAPI Specification

[earth2marsh]

🚀 Why this change?

The specification format formerly known as Swagger is now the OpenAPI Specification

📝 Related issues and Pull Requests

None

✅ What didn't I forget?

• To write docs
• To write tests
• To put Conventional Changelog prefixes in front of all my commits and run npm run lint

Since this is a docs-only fix, no tests or linting required.

[honzajavorek]

Hi, there are hundreds of references to Swagger throughout the docs, so if we want to change it, let's change it everywhere.

I'm wondering whether we want to do this at all, but I'm open to discussion. My thoughts: the format is still very well known and searched for as "Swagger". I'm aware of the renaming, but so far I decided to go with the naming like this:

• Reference the 2.0 version of the format consistently as Swagger
• Reference the 3.0 version of the format consistently as OpenAPI

The latter isn't in effect as #894 isn't done yet. When Dredd supports both, I'd call the formats Swagger 2.0 and OpenAPI 3.0, to clearly distinguish them. What do you think?

[honzajavorek]

Hi, thanks again for bringing it up. I filed a separate issue for discussing this: #994