documentation

Pull request #3767: feature/ZBX-26750-7.5-D-v2

Merge in WEB/documentation from feature/ZBX-26750-7.5-D-v2 to release/8.0

* commit '24bfb5e4eeef0a3c60650147d3e9807e8f3fc8a3':
  [ZBX-26750] restored changes.md/xliff
  [ZBX-26750] added "Python library for Zabbix" on Developer Center landing page
  [ZBX-26750] clarified "type" and "value_type" values
  [ZBX-26750] clarified send_value() format
  [ZBX-26750] added "Python library for Zabbix" section
  [ZBX-26750] prepared docs for new "Python library for Zabbix" section