lib: intro `Text::is_hex`

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib: intro libevent

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib: intro the web server nitcorn

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
examples: add two nitcorn examples

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>