Release 0.0.45

The only functional change in this version is the change from Markdown to
AsciiDoc. That is not really relevant because the generated documentation
isn't currently published.

In addition to that there also some changes to the development and build
workflows:

• Rename master branch to main.

  To adapt your local repository to the new branch name run the following
  commands:

  git branch -m master main
  git fetch origin
  git branch -u origin/main main
  git remote set-head origin -a

• Rewrite the publish release action in Python.

• Automatically add changes from CHANGES.md to release descriptions.