Multiline task description

**Is your feature request related to a problem? Please describe.**

Add random thoughts (pieces of information) to a task item.

**Describe the solution you'd like**

After creating a task it would be nice to add some pieces of information to it in a while. For example
`tb --edit 3`
will open full task description in your favorite editor (eg. vim). To view complete task\`s description
`tb --show 3`

**Additional context**

Start by tracing the CLI entry points for `tb --edit 3` and `tb --show 3`, then inspect how task data is stored and rendered. Check the existing command behavior and any related tests before deciding how multiline descriptions should be represented. Done means an existing task can be edited in the user's editor and its complete description is shown consistently.

Written by the indexing model from the issue text.