Short description to be shown as a tutorial's subtitle

The level is identified and distributed following the regex:

/^(##\s(?<levelId>L\d+)\s(?<levelTitle>.*)\n*(>\s*(?<levelSummary>.*))?\n+(?<levelContent>[^]*))/;

The Level can be split into steps or have no steps. Levels without steps are meant to be used as only informative content, for example: use a Level without steps at the end of the tutorial to congratulate the student and provide some additional related resources.

Tutorial's content. It can span through multiple paragraphs and use headers `####` and `#####`.

Steps are identified and their content described using the following regex:

/^(###\s(?<stepId>(?<levelId>L\d+)S\d+)\s(?<stepTitle>.*)\n+(?<stepContent>[^]*))/;

The numbers identifying the levels and steps are irrelevant but keep in mind that they will be executed in order. A level with id `10` will be executed before another one with id `20` and so on. These `ids` should have a match in the configuration file (`coderoad.yaml`).

Short description of the step's purpose. Should be short and fit in one line

**Important**

1. Both level and step ids must have an entry with the same id on the configuration file;

2. Step Ids are based on its level id. Any step from level `L234` must start with `L234S`, followed by the sequential digits.