add javadoc for ConfigCommands (#2833)

* add javadoc for ConfigCommands

* Apply suggestions from code review

Co-authored-by: M Sazzadul Hoque <7600764+sazzad16@users.noreply.github.com>

src/main/java/redis/clients/jedis/commands/ConfigCommands.java

@@ -2,18 +2,76 @@
 
 import java.util.List;
 
+/**
+ * The interface about managing configuration parameters of Redis server.
+ */
 public interface ConfigCommands {
 
+  /**
+   * Used to read the configuration parameters of Redis server.
+   *
+   * @param pattern config name
+   * @return config value of Redis server
+   */
   List<String> configGet(String pattern);
 
+  /**
+   * Used to read the configuration parameters of Redis server.
+   *
+   * @param pattern name of Redis server's configuration
+   * @return value of Redis server's configuration
+   */
   List<byte[]> configGet(byte[] pattern);
 
+  /**
+   * Used in order to reconfigure the Redis server at run time without
+   * the need to restart.
+   *
+   * @param parameter name of Redis server's configuration
+   * @param value     value of Redis server's configuration
+   * @return OK when the configuration was set properly.
+   * Otherwise, an error is returned.
+   */
   String configSet(String parameter, String value);
 
+  /**
+   * Used in order to reconfigure the Redis server at run time without
+   * the need to restart.
+   *
+   * @param parameter name of Redis server's configuration
+   * @param value     value of Redis server's configuration
+   * @return OK when the configuration was set properly.
+   * Otherwise, an error is returned.
+   */
   String configSet(byte[] parameter, byte[] value);
 
+  /**
+   * Resets the statistics reported by Redis using the INFO command.
+   * <p>
+   * These are the counters that are reset:
+   * <p>
+   * 1) Keyspace hits
+   * 2) Keyspace misses
+   * 3) Number of commands processed
+   * 4) Number of connections received
+   * 5) Number of expired keys
+   * 6) Number of rejected connections
+   * 7) Latest fork(2) time
+   * 8) The aof_delayed_fsync counter
+   *
+   * @return always OK.
+   */
   String configResetStat();
 
+  /**
+   * Rewrites the redis.conf file the server was started with, applying
+   * the minimal changes needed to make it reflect the configuration
+   * currently used by the server, which may be different compared to the
+   * original one because of the use of the CONFIG SET command.
+   *
+   * @return OK when the configuration was rewritten properly.
+   * Otherwise, an error is returned.
+   */
   String configRewrite();
 
 }