Improve Tutorial using user feedback

[emil14]

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[emil14]

@nbox363

1. Wasn't clear why we had to instantiate println fmt.Println instead of just -> fmt.Pritnln
2. In code blocks that show several files wasn't clear immidietely that they are different files
3. Maybe new command better scaffold empty project instead of hello world?
4. As a Go programmer - it wasn't obvious that we compile package and not project (that src is a package)
5. Wasn't clear what "message" is when we first talk about them in ## Components Section, this wording was proposed "An input port start that accepts masseges with any type"
6. When we first introduced nodes it wasn't obvious that println is a node
7. Wanted to see that components has 2 blocks - nodes and net, from the beginning
8. Wasn't clear what {} is (thought that this is an empty message)
9. Wanted to have definition for all base abstractions