* Updated documentation for 1.18.0 release with external components support.

* Moved example.yaml to the root dir, in line with the recommendations from the ESPHome external components guide.

* Normalized the version numbering for ESPHome references.

* Fixed the styling of the example.yaml references.

Co-authored-by: Maurice Makaay <mmakaay1@xs4all.net>

Co-authored-by: Maurice Makaay <mmakaay1@xs4all.net>

As I found out by just trying it out, the debug pad for GPIO2 can be used for I/O purposes. I managed to hook up a microwave presence sensor to the debug pad, with great success. The documentation is updated with that new knowledge.

Explained the need for a custom platform package for arduino-esp32 in the technical information.

I tried the codebase against the new esp-idf 4 alpha code, and
the build didn't have exception handling enabled by default.
I saw no problems with modifying the code to not raise exceptions,
so I did so to be future-proof.

The exception cases were cases that should not happen anyway,
because the input that could trigger the exception has already
been validated on beforehand by the Python-based code generation.