Added goal and ideas section to the main readme

Signed-off-by: artem.ivanov <[email protected]>

indy-besu/README.md

@@ -1,10 +1,43 @@
 # Indy ledger
 
-This project aims to provide a replacement for Hyperledger Indy blockchain that provides support for verifiable credentials.
+## Goals and ideas
+
+* Provide a replacement for [Hyperledger Indy](https://www.hyperledger.org/projects/hyperledger-indy) ecosystem that provides support for verifiable credentials:
+  * Components to replace:
+    * Distributed ledger: [Indy Node](https://github.com/hyperledger/indy-node) and [Indy Plenum](https://github.com/hyperledger/indy-plenum)
+    * Client library: [Indy SDK](https://github.com/hyperledger/indy-sdk/tree/main)
+  * Capability to migrate the data from the original Indy Ledger
+* Distributed ledger requirements:
+  * Public Permissioned Blockchain
+    * Control the validator nodes 
+    * Control the user permissions
+  * EVM compatible Blockchain
+    * Capability to deploy on different networks
+  * Based on existing open-source blockchain framework with a good performance, sufficient adoption, and wide community
+  * Capability to work without tokens and fees
+  * Stable consensus protocol
+* Functional requirements:
+  * Interoperability:
+    * Capability to use existing DID's and identifiers:
+      * Support [indy](https://hyperledger.github.io/indy-did-method/) DID method  
+      * Support [sov](https://sovrin-foundation.github.io/sovrin/spec/did-method-spec-template.html) DID method
+      * Identifiers previously stored on the client side should be resolvable on the new Ledger
+    * Capability to use the ledger as an [AnonCreds Registry](https://hyperledger.github.io/anoncreds-methods-registry/)
+    * Compatibility with the latest [AnonCreds Specification](https://hyperledger.github.io/anoncreds-spec/)
+  * Extensibility: 
+    * Capability to integrate new pieces of functionality easily
+    * Capability to use [ETHR](https://github.com/decentralized-identity/ethr-did-resolver/blob/master/doc/did-method-spec.md) DID method
+      * Integration with the [AnonCreds Registry](https://hyperledger.github.io/anoncreds-methods-registry/)
+      * Integration with `Permissioned` modules
+  * Data validity:
+    * Neglect `gas` efficiency in favour general validation of the stored data
+      * Basic [DID Documents](https://www.w3.org/TR/did-core/) validation
+      * Basic [AnonCreds entities](https://hyperledger.github.io/anoncreds-spec/#anoncreds-setup-data-flow) validation
+      * Basic state consistency validation
 
 ## Design documentation
 
-See [README.md](/docs/README.md).
+See [design document](./docs/README.md) covering the main ledger aspects.
 
 ## Running local network