Add back size comment

src/lib/core/TLVReader.cpp

@@ -767,6 +767,7 @@ CHIP_ERROR TLVReader::ReadElement()
     // length bytes (if present), and for elements that don't have a length (e.g. integers), the value bytes.
     const uint8_t elemHeadBytes = static_cast<uint8_t>(1 + tagBytes + valOrLenBytes);
 
+    // 17 = 1 control byte + 8 tag bytes + 8 length/value bytes
     uint8_t stagingBuf[17];
 
     // Odd workaround: clang-tidy claims garbage value otherwise as it does not