Image and rendering fixes

[mmattel]

This PR fixes the following:

• Nearly all images needed a sizing fix to improve rendering
• Image positioning
• Table centering where necessary
• Table fixes
• Removing unneeded index.adoc files from the navigation

No content changes.

Backport to 5.2

[mmattel]

In a nutshell:

image: adds the image "inline" with text, means it aligns where the next character would be.

image:: always centers the text in the frame (page or table etc), used where the image stands on its own.

More details if you search for asciidoc image. I will add a link tomorrow morning so you can read the details about if you like.

[mmattel]

@phil-davis fyi: https://docs.asciidoctor.org/asciidoc/latest/macros/images/