[hotfix][docs] Fix typos in BatchTask, MutableRecordReader and Priori…

flink-runtime/src/main/java/org/apache/flink/runtime/io/network/api/reader/MutableRecordReader.java

@@ -36,7 +36,7 @@ public class MutableRecordReader<T extends IOReadableWritable> extends AbstractR
      * can spill partial records to disk, if they grow large.
      *
      * @param inputGate The input gate to read from.
-     * @param tmpDirectories The temp directories. USed for spilling if the reader concurrently
+     * @param tmpDirectories The temp directories. Used for spilling if the reader concurrently
      *     reconstructs multiple large records.
      */
     public MutableRecordReader(InputGate inputGate, String[] tmpDirectories) {

flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/PrioritizedDeque.java

@@ -70,7 +70,7 @@ public void addPriorityElement(T element) {
                 priorPriority.addFirst(deque.poll());
             }
             deque.addFirst(element);
-            // readd them before the newly added element
+            // read them before the newly added element
             for (final T priorityEvent : priorPriority) {
                 deque.addFirst(priorityEvent);
             }

flink-runtime/src/main/java/org/apache/flink/runtime/operators/BatchTask.java

@@ -825,7 +825,7 @@ protected void initLocalStrategies(int numInputs) throws Exception {
         this.inputIsAsyncMaterialized = new boolean[numInputs];
         this.materializationMemory = new int[numInputs];
 
-        // set up the local strategies first, such that the can work before any temp barrier is
+        // set up the local strategies first, such that they can work before any temp barrier is
         // created
         for (int i = 0; i < numInputs; i++) {
             initInputLocalStrategy(i);