Documentation: API Security updates for DAST

Main issue - #327070 (closed) Design issue - #348725 (closed)

Context

We're adding support for 3 API scan methods, similar to API fuzzing:

1. HTTP Archive (HAR)
2. OpenAPI
3. Postman Collection

Proposal

This issue is to add documentation updates to https://docs.gitlab.com/ee/user/application_security/dast/#site-profile to support two new options:

• "Scan method", and
• "Scan file path"

Note: The changes are currently in development and will be rolled out with feature flag - #345837 (closed)