improve manual entry of assignment to a data frame

[bkamins]

Fixes #3200

[nalimilan]

I'm not sure it's the place to mention this kind of thing. Getting Started is supposed to be a simple illustration of basics using examples. This is more like reference documentation which risks scaring newcomers.

[bkamins]

Yes - I was also thinking about it. The problem is:

What should we write to avoid users thinking that df[!, :col] is non copying also in broadcasted assignment. Users repeatedly report that they read in Getting Started about it and I every time need to explain that getindex is not the same as broadcast! or setindex!.

I think we should write something. The question is what then?

[nalimilan]

Maybe add a short explanation/example in the section right before "Constructing Column by Column"? Mentioning all rules would be too complex but maybe a few words are enough to explain the essentials?

[bkamins]

OK - I have changed it to use examples.

I have also reviewed basics.md. Interestingly it was more precise and mostly good because it is fresher (I just needed to change two sentences - I marked them with a comment). The rest of changes is improving line breaks as the source did not look good to me.

[bkamins]

Thank you. Once the CI passes on main I will tag a new release.