Document the version field required in dependabot.yaml

[wolf99]

AFAICT the only mention of a value for the version field to be used in the dependabot.yaml is in the example on the following page, which indicates a value of 2.

https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuring-dependabot-version-updates

The description in the text reads an excedingly terse:

2. Add a version.

No indication of what this is the version of nor which version is current, nor what is different between versions.

I'm guessing that the version in this file is for the version of the API for this file rather than of dependabot implementation itself ?
But this is not explained.

I cant see this field or the value for it mentioned anywhere else in the GitHub documentation.
The tags on the dependabot-core repository do not appear to be related.

Searching the internet for any permutation including the words "dependabot" and "version" of course outputs many thousands of results for managing versions of other things using dependabot.