• updated docblocks to be less USG-specific
  
• removed content-length header from the logout method, reported by @Olivier6767
  
• added notes to reflect successful tests with UDR running the latest Pre-Release version of the UniFi controller (version 6.5.52)
  
• added checks in specific cases when using trim() to prevent PHP 8 from throwing an error when the variable is null, submitted by @djchen