HDFS-17228. Improve documentation related to BlockManager. (#6195). Contributed by JiangHua Zhu.

Reviewed-by: Inigo Goiri <inigoiri@apache.org>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -150,10 +150,10 @@ import org.slf4j.LoggerFactory;
  * redundancy.
  *
  * For regular replication, # of min live replicas for maintenance is determined
- * by DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_KEY. This number has to <=
- * DFS_NAMENODE_REPLICATION_MIN_KEY.
+ * by {@link DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_KEY}. This number has to <=
+ * {@link DFS_NAMENODE_REPLICATION_MIN_KEY}.
  * For erasure encoding, # of min live replicas for maintenance is
- * BlockInfoStriped#getRealDataBlockNum.
+ * {@link BlockInfoStriped#getRealDataBlockNum}.
  *
  * Another safety property is to satisfy the block placement policy. While the
  * policy is configurable, the replicas the policy is applied to are the live