Support Analysis Suggestions in Approaches

## Expected Behavior
The project should support the description of "analysis suggestions" in the approach definition file. I would propose a new subsection `suggestion` under the `view` section.

There are cases, where typical (malicious) activity has similarities from one threat actor to another. It would be helpful to integrate such hints, so that analysts can get an idea what to look for.

## Actual Behavior
Feature not included.

## Steps to Reproduce the Problem
not applicable

## Specifications

- Version: 1.0.0
- Platform: not applicable