[hotfix] Fix the typo in comments (alibaba#202)

Author: Aitozi

fluss-server/src/main/java/com/alibaba/fluss/server/kv/KvTablet.java

@@ -409,7 +409,7 @@ public void flush(long exclusiveUpToLogOffset, FatalErrorHandler fatalErrorHandl
                 kvLock,
                 () -> {
                     // when kv manager is closed which means kv tablet is already closed,
-                    // but the tablet server may still handles fetch log request from follower
+                    // but the tablet server may still handle fetch log request from follower
                     // as the tablet rpc service is closed asynchronously, then update the watermark
                     // and then flush the pre-write buffer.
 

fluss-server/src/main/java/com/alibaba/fluss/server/replica/Replica.java

@@ -488,7 +488,7 @@ public void checkProjection(@Nullable int[] projectedFields) {
     private void onBecomeNewLeader() {
         if (isKvTable()) {
             // if it's become new leader, we must
-            // fist destroy the old kv tablet
+            // first destroy the old kv tablet
             // if exist. Otherwise, it'll use still the old kv tablet which will cause data loss
             dropKv();
             // now, we can create a new kv tablet