Chore/documentation improvements

[picciama]

PR Checklist

• This comment contains a description of changes (with reason)
• Referenced issue is linked
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

Description of changes

• missing functions added to API documentation
• examples for minimal configurations added to utils module
• removed old example_config.json and documentated how to import minimal configs
• updated oktoberfest logo to contain the text as path instead of font
• fixed wrong documentation of missedCleavages key and other minor config documentation errors

Technical details

Additional context

[tobiasko]

🥳