[OTel Docs] Indent batch config (elastic#10787)

This updates the `batch` config to match the nesting in elastic#10569.

Author: pickypg

docs/reference/edot-collector/config/default-config-standalone.md

@@ -116,10 +116,10 @@ otlp/ingest:
     sizer: bytes
     queue_size: 50000000 # 50MB uncompressed
     block_on_overflow: true
-  batch:
-    flush_interval: 1s
-    min_size: 1_000_000 # 1MB uncompressed
-    max_size: 4_000_000 # 4MB uncompressed
+    batch:
+      flush_interval: 1s
+      min_size: 1_000_000 # 1MB uncompressed
+      max_size: 4_000_000 # 4MB uncompressed
 ```
 
 The previous configuration leverages an in-memory queue and optimized batching defaults to improve throughput, minimize data loss, and maintain low end-to-end latency.