docs/examples.rst: Fix code block issue (#214)

* Use and define [tools.setuptools.packages.find]

Setuptools found a subdirectory or module named selectolax.lexbor
in the source code, but it wasn't explicitly
included in the list of packages to be installed.

* docs/examples.rst: Fix code block issue

Docutils/Sphinx expects a blank line after an indented block (
code, quote, list) before the block ends or a new block begins.

Author: schoekek

docs/examples.rst

@@ -231,6 +231,7 @@ They can be called on any node.
 **Output:**
 
 .. code-block:: text
+
     Inner html:
 
       <div>Hi there</div>