add dlt docu snippet

docu/Concepts/DLT/overview.md

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+# DLT-Connector Overview
+
+What the DLT Connector does roughly.
+
+- create transaction
+- receive transactions from iota
+- warmup, load missing transactions from iota on startup
+
+## create transaction 
+- called from backend with transaction details
+  - sender user | signing user (in case of contribution)
+    - uuid
+    - account nr | default = 1  
+    - community uuid
+  - recipient user 
+    - uuid
+    - account nr | default = 1  
+    - community uuid
+  - amount
+  - memo 
+  - type
+  - createdAt
+- load or create accounts
+- compose protobuf transaction
+- derive correct private key for signing account and sign transaction
+- validate transaction
+- write transaction into transaction_recipes table
+- send transaction to iota
+- update iota message id in transaction_recipes table
+- return to backend with iota message id
+
+
+## receive transactions from iota
+- listen on all registered community topics on iota
+- make sure we have everything from milestone
+- sort per community by iota milestone, createdAt ASC
+- per message:
+  - deserialize to protobuf object
+  - validate
+  - if valid:
+    - calculate running_hash and account_balance
+    - write into confirmed_transactions
+  - if invalid: 
+    - write into invalid_transactions
+  - send request to backend with final transaction data for comparison
+    - sender user | signing user (in case of contribution)
+      - uuid
+      - account nr 
+      - community uuid
+    - recipient user 
+      - uuid
+      - account nr
+      - community uuid
+    - amount 
+    - memo
+    - createdAt
+    - confirmedAt
+    - type
+    - iota message id
+    - balance for createdAt
+    - decay for createdAt
+
+## warmup, load missing transactions from iota or Chronicle on startup
+- read all iota message ids from all registered topics
+- check if already exist
+- load details for not existing message ids
+- do for every message [receive](#receive-transactions-from-iota)