Merge branch '88-add-section-with-log-description' into 'dux'

## Inject logging structure

The logs for this project are stored on the path specified in `INJECT_LOGS`,

which is set to `backend-logs.jsonl` by default.

### Format

The log file contains messages in the JSONL [format](https://jsonlines.org/).

Each message contains these fields:

- `module` - module where this message originates from

- `level` - log level, can be either `INFO`, `WARNING` or `ERROR`

- `date` - timestamp when the message was created

- `lineno` - line number

- `message` - the message text

### Troubleshooting

The logs contain quite a few messages and most of them won't be useful to admins for

figuring out why the platform does not behave as expected.

This is because the exercise is quite a complex state machine,

therefore we log all actions that happen during the exercise to help developers replicate bugs.

However, despite this _all_ `WARNING` and `ERROR` level logs should be considered when checking logs.

These logs might hint at the possible reasons why something does not work.

### Troubleshooting tips

- When debugging the process of sending emails with credentials,

    you can search for the word `credentials` in the `message` field.

    This should return _all_ logs related to sending these emails.

      - Upgrade definition: tech/architecture/definitions/upgrade.md

      - CHANGELOG: tech/architecture/definitions/CHANGELOG.md

    - Exercise log format: tech/log-format.md

    - Platform backend logs: tech/platform-logs.md

    - Version compatibility: tech/version-compatibility.md

  - How to prepare an exercise?:

    - INJECT Process: INJECT_process/intro/overview.md