fix(docs): Fix indentation in route_bc_or_cd function (#1184)

## Overview
Fix indentation in route_bc_or_cd function

## Type of change

**Type:** Fix formatting

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- [ ] All code examples have been tested and work correctly
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## Additional notes
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Author: 35bytes

src/oss/langgraph/use-graph-api.mdx

@@ -2116,9 +2116,9 @@ Your conditional edges can route to multiple destination nodes. For example:
 :::python
 ```python
 def route_bc_or_cd(state: State) -> Sequence[str]:
-if state["which"] == "cd":
-return ["c", "d"]
-return ["b", "c"]
+    if state["which"] == "cd":
+        return ["c", "d"]
+    return ["b", "c"]
 ```
 :::