Improve documentation site with API reference as is in v2 client

[bednar]

Documentation is auto created at readthedocs.io - https://influxdb3-python.readthedocs.io/en/stable/.

Improve documentations for v3 client:

• Add API reference
• Remove link to old documentation -

  influxdb3-python/influxdb_client_3/write_client/client/write_api.py

  Line 298 in 503a75e

  - https://influxdb-client.readthedocs.io/en/stable/usage.html#how-to-use-asyncio

• Add link to documentation to header of the README.md