v7.3: update user doc for multirocksdb (pingcap#14371)

partitioned-raft-kv.md

@@ -37,6 +37,11 @@ Partitioned Raft KV has the following restrictions:
 
 * It does not support EBS volume snapshot backup yet.
 * It does not support online unsafe recovery or Titan yet.
-* It does not support the tikv-ctl command-line tool yet.
+* It does not support the following subcommands of the tikv-ctl command-line tool:
+    * `unsafe-recover`
+    * `raw-scan`
+    * `remove-fail-stores`
+    * `recreate-region`
+    * `reset-to-version`
 * It is not compatible with TiFlash yet.
 * You cannot enable or disable this feature after the cluster is initialized.

tikv-configuration-file.md

@@ -1432,7 +1432,9 @@ Configuration items related to `rocksdb.defaultcf`, `rocksdb.writecf`, and `rock
 
 + Memtable size
 + Default value for `defaultcf` and `writecf`: `"128MB"`
-+ Default value for `lockcf`: `"32MB"`
++ Default value for `lockcf`:
+    + When `storage.engine="raft-kv"`, the default value is `"32MB"`.
+    + When `storage.engine="partitioned-raft-kv"`, the default value is `"4MB"`.
 + Minimum value: `0`
 + Unit: KB|MB|GB
 
@@ -1721,6 +1723,8 @@ Configuration items related to `raftdb`
 
 + The maximum RocksDB WAL size in total
 + Default value: `"4GB"`
+    + When `storage.engine="raft-kv"`, the default value is `"4GB"`.
+    + When `storage.engine="partitioned-raft-kv"`, the default value is `1`.
 
 ### `compaction-readahead-size`
 
@@ -1875,7 +1879,9 @@ Configuration items related to Raft Engine.
 + Value Options:
     + `1`: Default log file version for TiKV earlier than v6.3.0. Can be read by TiKV >= v6.1.0.
     + `2`: Supports log recycling. Can be read by TiKV >= v6.3.0.
-+ Default value: `2`
++ Default value:
+    + When `storage.engine="raft-kv"`, the default value is `2`.
+    + When `storage.engine="partitioned-raft-kv"`, the default value is `5`.
 
 ### `enable-log-recycle` <span class="version-mark">New in v6.3.0</span>