Move section in datastructures to storage

docs/wiki/EL/el-architecture.md

@@ -230,14 +230,25 @@ In Ethereum two primary types of transaction pools are recognized:
 
 ### Data structures
 
-Blockchain and state data processed by execution client need to be stored in the disk. These are necessary to validate new blocks, verify history and to serve peers in the network. Client stores historical data, also called the ancient database, which include previous blocks. Another database of trie structure contains the current state and small number of recent states. In practice, clients keep various databases for different data categories. Each client can implement a different backend to handle this data, e.g. leveldb, pebble, mdbx.
-
 More details in the page on [EL data structures](/wiki/EL/data-structures.md).
 
 #### RLP
 
 [Wiki - RLP](/wiki/EL/RLP.md)
 
-### StateDB
+### Storage
+
+Blockchain and state data processed by execution client need to be stored in the disk. These are necessary to validate new blocks, verify history and to serve peers in the network. Client stores historical data, also called the ancient database, which include previous blocks. Another database of trie structure contains the current state and small number of recent states. In practice, clients keep various databases for different data categories. Each client can implement a different backend to handle this data, e.g. leveldb, pebble, mdbx.
+
+**Leveldb** 
 
 TODO
+
+**Pebble** 
+
+TODO
+
+**MDBX**.
+
+Read more about its [features](https://github.com/erthink/libmdbx#features). Additionally, boltdb has a page on comparisons with other databases such as leveldb, [here](https://github.com/etcd-io/bbolt#comparison-with-other-databases). The comparative points mentioned on bolt are applicable to mdbx.   
+