rpc: add documentation for genesis chunked api (#6776)

CHANGELOG_PENDING.md

@@ -24,6 +24,7 @@ Friendly reminder: We have a [bug bounty program](https://hackerone.com/tendermi
   - [fastsync/rpc] \#6620 Add TotalSyncedTime & RemainingTime to SyncInfo in /status RPC  (@JayT106)
   - [rpc/grpc] \#6725 Mark gRPC in the RPC layer as deprecated.
   - [blockchain/v2] \#6730 Fast Sync v2 is deprecated, please use v0
+  - [rpc] Add genesis_chunked method to support paginated and parallel fetching of large genesis documents.
 
 - Apps
   - [ABCI] \#6408 Change the `key` and `value` fields from `[]byte` to `string` in the `EventAttribute` type. (@alexanderbez)

rpc/openapi/openapi.yaml

@@ -806,6 +806,7 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ErrorResponse"
+
   /genesis:
     get:
       summary: Get Genesis
@@ -813,7 +814,7 @@ paths:
       tags:
         - Info
       description: |
-        Get genesis.
+        Get the genesis document.
       responses:
         "200":
           description: Genesis results.
@@ -827,6 +828,39 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ErrorResponse"
+
+  /genesis_chunked:
+    get:
+      summary: Get Genesis in paginated chunks
+      operationId: genesis_chunked
+      tags:
+        - Info
+      description: |
+        Get genesis document in a paginated/chunked format to make it
+        easier to iterate through larger gensis structures.
+      parameters:
+        - in: query
+          name: chunkID
+          description: Sequence number of the chunk to download.
+          schema:
+            type: integer
+            default: 0
+            example: 1
+      responses:
+        "200":
+          description: Genesis results.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/GenesisChunkedResponse"
+        "500":
+          description: Error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorResponse"
+
+
   /dump_consensus_state:
     get:
       summary: Get consensus state
@@ -1894,6 +1928,35 @@ components:
                   properties: {}
                   type: object
 
+    GenesisChunkedResponse:
+      type: object
+      required:
+        - "jsonrpc"
+        - "id"
+        - "result"
+      properties:
+        jsonrpc:
+          type: string
+          example: "2.0"
+        id:
+          type: integer
+          example: 0
+        result:
+          required:
+            - "chunk"
+            - "total"
+            - "data"
+          properties: 
+            chunk:
+              type: integer
+              example: 0
+            total:
+              type: integer
+              example: 1
+            data: 
+              type: string
+              example: "Z2VuZXNpcwo="
+
     DumpConsensusResponse:
       type: object
       required: