Changes

<span style="color:red;font-weight:bold">In December 2022, the X820 metal case has been updated to a new version, we name it <span style="color:red;font-weight:bold">'''X820-C6'''</span>.The X820-C6 metal case is redesigned to be compatible with Raspberry Pi 3B+/3B& X820 V3.0/X821 & X735. You can use this X820-C6 case with Raspberry Pi 3B+/3B+X820 V3.0+X735 OR Raspberry Pi 3B+/3B+X821+X735.</span>