Mention development environment prerequisites in DG

[le0tan]

What is the purpose of this pull request? (put "X" next to an item, remove the rest)

• [X] Documentation update

What is the rationale for this request?

If someone follows the DG, he will probably encounter unexplained error messages.

What changes did you make? (Give an overview)

I added an optional paragraph in the Requirement section of the developer guide, describing the dependencies needed for puml.

Provide some example code that this change will affect:

n/a

Is there anything you'd like reviewers to focus on?

n/a

Testing instructions:

n/a

Proposed commit message: (wrap lines at 72 characters)

Update UG on PUML dependencies.

There was no description of MarkBind's optional dependency on Java and Graphviz, if someone followed the DG, he would encounter unexplained error messages. Add some info on such descriptions would make getting started easier.

[yamgent]

Thanks for your PR @le0tan.

Regarding the additions, it seems a bit odd to put this part here, because the "Requirements" section is talking about the knowledge required for this project, rather than the tools required. Perhaps this is more appropriate under the "Development Process" section? You can create a "Prerequisite" section (that is before the "Development" section talking about cloning the repo), and put all of the version required there.

Also, I think developers wouldn't have a choice of whether they want to install these additional dependencies, because PlantUML is a default plugin of MarkBind, not optional, so we will definitely need them at some point, for example during the tests which you ran. So I wouldn't say that it is "optional". (Users on the other hand have this flexibility, as they may not use PlantUML on their website at all)

[yamgent]

Also the commit title is way too long, the hard limit is 72 characters before GitHub cuts it off. Preferably commit title should be 50 characters, but this soft limit can be relaxed only if it is hard to make the intent concise.

[yamgent]

Thanks for your changes.

The title of your PR and commit can be more specific to the changes involved. I suggest something like "Mention development environment prerequisites in DG"