[ISSUE#159] Fix DLedgerClient the log format is incorrect (#160)

Author: mxsm

src/main/java/io/openmessaging/storage/dledger/client/DLedgerClient.java

@@ -77,7 +77,7 @@ public AppendEntryResponse append(byte[] body) {
             return response;
         } catch (Exception e) {
             needFreshMetadata();
-            logger.error("{}", e);
+            logger.error("Append error", e);
             AppendEntryResponse appendEntryResponse = new AppendEntryResponse();
             appendEntryResponse.setCode(DLedgerResponseCode.INTERNAL_ERROR.getCode());
             return appendEntryResponse;