feat: Added in-memory storage for testing purposes

Author: Harshdev098

rust/README.md

@@ -24,6 +24,8 @@ cargo build --release
    ```
    cargo run -- server/vss-server-config.toml
    ```
+
+   **Note:** For testing purposes you can edit `vss-server-config.toml` to use `store_type` as in-memory instead of PostgreSQL: `store_type = "in_memory"`
 4. VSS endpoint should be reachable at `http://localhost:8080/vss`.
 
 ### Configuration