Improve references to C IDF documentation

[taunusflieger]

We should have an explicit reference to the C IDF documentation in case of std as the concepts there apply to Rust esp-idf-* as well. Some of the questions in the Matrix chat could have been self answered if people would have looked into the IDF documentation

[SergioGasquez]

Thanks for the feedback, I will add some references to esp-idf documentation