[hotfix] Fix comment typo (#586)

Author: yx9o

fluss-common/src/test/java/com/alibaba/fluss/memory/TestingMemorySegmentPool.java

@@ -54,12 +54,12 @@ public long totalSize() {
 
     @Override
     public void returnPage(MemorySegment segment) {
-        // do noting.
+        // do nothing.
     }
 
     @Override
     public void returnAll(List<MemorySegment> memory) {
-        // do noting.
+        // do nothing.
     }
 
     @Override

fluss-server/src/main/java/com/alibaba/fluss/server/utils/RpcGatewayManager.java

@@ -104,7 +104,7 @@ public CompletableFuture<Void> removeServer(int serverId) {
 
     @Override
     public void close() throws Exception {
-        // do noting.
+        // do nothing.
     }
 
     private class ServerRpcGateway {