Convert xdoc (without parsing) to Markdown

[Bukama]

After by tests of HTTP meta properties (see results DOXIASITETOOLS-358) I converted all of those xdoc files to Markdown where no parsing/calculation happens. We can do this when we have a parser for this.

Please note

General

• HTTP standard about meta tag for author (<meta name="author" content="name of author">) does not define an attribute for the email of the author. The content of those (like in mojo-api-specification.xml is not converted regardless of xdoc or markdown).

In the articles.md:

I did the following changes

• updated or removed links to buy the books,
• updated the link to the video
• changed the divs to a table for a more similar layout and because inside of divs not markdown is possible and I didn't want to copy all HTML.

I did not

• updated the articles list, even that there a tons of not-exists-anymore or unsafe (http instead of https) links,
• added the text and video of Karl Heinz (see Added Video Link. #324)

Simply because I realized that it's far more than transformation then. I would like to update the list and add Karl Heinz's video and other articles and videos to the list in a separate PR (pr an updated 324).

In the mojo-api-specification.md

• I moved the sentence about Maven 4 to the top, similar to the "multi module guide" and added Maven 3 to the tile
• I did not converted the commented out code, which is not rendered by the xdoc converter at the moment too, so no content loss here

In the repository.index.md
I did copy the image map, because I'm not happy yet with my plantUML image. Therefore I also moved the .odgfiles.

In the scm.md
I added table headers and created own tables for each section (on live there are partly filled table rows used as in between headers).

[Bukama]

Converted to draft, because I remembered that I wanted to add the JIRA links for the plugins (instead)

[Bukama]

Added issue links and rebased after master's changes. Ready for review.

[slawekjaranowski]

Next issue for markdown ... in version generated from xdoc we have <object ...> in output html.
With img tag links in svg are not working ...

@kwin @michael-o can you look?

[slawekjaranowski]

ok, I see we can add a html code to markdown ... so should be
<object ..../> as in old document version

[Bukama]

Updated:
Note Manual

tags needed to align the images below each other. Without them they were all next to each other

[slachiewicz]

Good to go, we can improve later