Revise Descriptions When OSCAL Content Sent by Client

[brian-comply0]

Description

As a developer issuing OSCAL REST API calls to send OSCAL content, I need to understand how to identify the OSCAL format I sending.

Acceptance Criteria

• [ ] For each model, the description for the following endpoints is updated as defined below
  • [x] POST /[model-name]
  • [x] PUT /[model-name]/{Identifier}

Description Content

The current description should be maintained for each of the two endpoints, with the following added to that content:

The client must include the `Content-type` HTML header and set it to one of the following:
- `application/json` when sending an OSCAL file in JSON format;
- `application/xml` when sending an OSCAL file in XML format; or
- `application/yaml` when sending an OSCAL file in YAML format.

The implementation _must_ accept all three OSCAL formats. OSCAL content sent to the server in any one of the three formats _must_ be made available in all three formats for the relevant GET method/endpoint combinations.

[brian-comply0]

@mpemy This has been addressed for the POST methods in PR #72 as required; however, this has not yet been addressed for PUT /[model-name]/{Identifier}
Moving to sprint 67.

[brian-comply0]

POST and PUT have now both been addressed in PR #72.