Fix typo in Memory Management documentation (#8827)

Summary: Pull Request resolved: #8827

Reviewed By: Yuhta

Differential Revision: D54414801

Pulled By: mbasmanova

fbshipit-source-id: 6d4b9d2de5b2ab634009e76c07d9004e0b5324af

velox/docs/develop/memory.rst

@@ -406,7 +406,8 @@ Memory Pool Management
      std::unique_ptr<MemoryReclaimer> reclaimer = nullptr);
 
   /// Create an aggregate child memory pool which allows to create child memory
-  /// pools from it, and it used to aggregate memory usage from its child pools. /// Aggregate memory pool is not allowed to allocate memory directly.
+  /// pools from it, and it used to aggregate memory usage from its child pools.
+  /// Aggregate memory pool is not allowed to allocate memory directly.
   virtual std::shared_ptr<MemoryPool> MemoryPool::addAggregateChild(
      const std::string& name);