add documentation on pre and post hooks to builder methods

[upachler]

I took the liberty and added some docs, hope this meets the requirements.

[ahl]

Let's update this in light of #933?

[upachler]

Hi @ahl, I adapted the docs as promised. However, apparently cargo fmt -- --check is now complaining about style (see below) - but I can't see anything wrong. When run locally, there is no output. I'm puzzled. Any clues? Or is this a Windows/Linux thing (I'm using a Windows machine ATM).

[ahl]

You can run cargo fmt and it will fix things. In this case, you have trailing spaces at the end of some lines.

[upachler]

ok thanks, seems that did it

[upachler]

@ahl: IMHO this should be ready to merge, what do you think?

[upachler]

Updated to resolve merge conflict.
@ahl Waiting for authorization. This is a documenation improvement, no code change