doc: add extension to handle HTML redirects

Handle redirects for moved pages. This extension is originally from the
ESP32 project and is maintained here:

https://github.com/espressif/esp-idf/blob/master/docs/html_redirects.py



Commit b240a181b7215158ef4db22ee7e694f938868502

Signed-off-by: Anas Nashif <anas.nashif@intel.com>