Add "user tutorial plus develop" to "develop"

[greengypsy]

• Added user tutorial
  • Added paths with styling
  • Added variables

All @jpfeuffer's changes have been merged into this branch. Closes #133. View the build here.

PR checklist

• [ ] I have added description of the change I'm proposing in the OpenMS Documentation.
• [ ] I have read and followed OpenMS Documentation Contributing guidelines.
• [ ] I have attached a screenshot of the relevant area after this change.
• [ ] CHANGELOG.md is updated.
• [ ] I have added my name in CONTRIBUTING.md.

[jpfeuffer]

Please doublecheck the links and remove links that do not make sense (e.g. with variables inside them, e.g. "YOUR_KNIME_VERSION"). See github actions result

[greengypsy]

@jpfeuffer I have fixed some broken links. The following links require clarification:

• http://www.mprophet.org/
• http://update.knime.com/community-contributions/trusted/4.6/ (forbidden)
• http://update.knime.org/analytics-platform/4.6.0
• http://update.knime.org/community-contributions/trusted/4.6.0:
• http://update.knime.org/community-contributions/trunk
• https://pyopenms.readthedocs.io/en/latest/datastructures.html