fix: Add API spec limits and versioning system info

## Definition of done
- Document that there is an 8MB limit on API spec content in [validation](https://developer.konghq.com/dev-portal/apis/#api-spec-validation).
- Document that the API entity (`/apis`) will be the major version and `api/:id/versions` is the minor version, and the slug is formed like `{apiname}+{semver major|version}` in the following pages:
- https://developer.konghq.com/dev-portal/apis/#api-versioning
- (in steps 1 & 2 explain this and adjust curl/TF examples to match) https://developer.konghq.com/how-to/automate-api-catalog/ and https://developer.konghq.com/how-to/automate-api-catalog-with-terraform/

## Information
DRP: Jason Harmon

## Size
Small

Open the linked API validation and versioning pages, then review the two API catalog automation guides and their steps 1 and 2, including the curl and Terraform examples. Document the 8MB API spec limit, explain the major/minor version relationship and slug format, and update the examples so all four pages match the definition of done.

Written by the indexing model from the issue text.