Filter expert: Docs fix, treat false as false for filter_regex and add logging

[sebix]

• Docs: fix syntax in filter expert bot documentation
• filter expert: treat filter_regex false as False if the parameter

  filter_regex: false
  

  was set, the bot treated this as true with this patch, false is treated as false
• filter expert: add debugging output for comparisons if users or devs run the bot in DEBUG log level, there was no useful output yet. This change adds two log statements, showing which comparision was made