Make interface to write_i2c_block_data more robust and cleanup some docs

[matteius]

I got some code that was intended for the Raspberry Pi running on the pico tonight for the BME280 sensor, and I used this library to supply the smbus module that was being requested. The library though was passing in an int in a list to the method write_i2c_block_data which currently doesn't handle that case. I feel this refactor handles a multitude of cases more than the current logic and have opened this PR to suggest the change.