add some detail about floating number types

[vladak]

I had a revelation recently about a particular use case (different language, different context - adafruit/Adafruit_CircuitPython_MiniMQTT#176) about floating point types which prompted me to realize that we should probably mention some of the floating point type characteristics in the lecture, specifically about the loss of precision when adding up a floating value. Maybe some basic introduction to the IEEE 754 Floating-Point Standard. Nothing too detailed, just warn the students about the pitfalls when working with such numbers, similarly to what we do with integer overflow and such. This is probably a topic that should be covered in some other lecture, however my suspicion is that this is not covered anywhere within the faculty curriculum.

[vladak]

I already added https://github.com/devnull-cz/c-prog-lang/blob/master/src/float-precision.c to demonstrate limited precision.