add readme

README.md

@@ -1 +1,37 @@
-# ll-bridge-api
+# ll-bridge-api
+
+Indexer & API for the LightLink standard bridge.
+
+Indexes deposits & withdrawals and automatically monitors and updates their status.
+
+## API
+
+A HTTP API is available at `/v1/`
+
+### Transactions
+
+It returns a list of transactions that match the query.
+
+Query parameters:
+
+- `type` - filter by type (withdrawal or deposit)
+- `status` - filter by status
+- `from` - filter by from address
+- `to` - filter by to address
+- `page` - pagination
+- `page_size` - pagination
+
+i.e. `GET /v1/transactions?type=withdrawal&status=READY_TO_PROVE&page=1&page_size=10`
+
+## Withdrawal Status Flow
+
+    1. STATE_ROOT_NOT_PUBLISHED (New Withdrawal submitted on L2)
+    2. READY_TO_PROVE (After 6-12 hours, user can prove withdrawal on L1)
+    3. IN_CHALLENGE_PERIOD (Withdrawal has been proven on L1. Challenge period started on L1, wait 7 days)
+    4. READY_FOR_RELAY (Challenge period ended on L1, user can now relay withdrawal on L1)
+    5. RELAYED (Message sent to L2)
+
+## Deposit Status Flow
+
+    1. READY_FOR_RELAY (New Deposit submitted on L1)
+    2. RELAYED (Deposit complete on L2 automatically by Sequencer)