improve freenet library documentation

[gogo2464]

I have some issues to contribute. I do not understand the goal of some functions. Could you improve some doc please?

[sanity]

Not specific enough for an issue.

[gogo2464]

I would like to:

• details any potential issue on building and running freenet. EG: tell to ignore tsc errors in the tutorial
• create a use case of real apps
• link api ref from docs.rs for developper directly in https://docs.freenet.org/ for dev
• vulgarize some maths in the last chapter

can you open it again please?

[gogo2464]

also the doc there https://docs.freenet.org/introduction.html is already very good!

I am just wandering if it could respect this typology:

https://www.writethedocs.org/videos/eu/2017/the-four-kinds-of-documentation-and-why-you-need-to-understand-what-they-are-daniele-procida/

[gogo2464]

We should also mention that in case of broken issue, the commit got from

git reset --hard 8ef468f511c8edc784999778553587b483cfdeb6

is stable enough for dev!