add support for example blocks

[ggrossetie]

Since Markdown does not support example block, we should probably extract the content.

.Onomatopoeia
====
The book hit the floor with a *thud*.

He could hear doves *cooing* in the pine trees`' branches.
====

*Onomatopoeia*\
The book hit the floor with a **thud**.

He could hear doves **cooing** in the pine trees’ branches.

Onomatopoeia
The book hit the floor with a thud.

He could hear doves cooing in the pine trees’ branches.