Bug fix: Correct indentation of an iteration substep (#522)

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Author: inexorabletash

index.bs

@@ -4580,7 +4580,7 @@ partial interface MLGraphBuilder {
     1. If |shapeA|[|sizeA| - 1] is not equal to |shapeB|[0], then [=exception/throw=] an "{{OperationError}}" {{DOMException}}.
     1. Let |shape| be an array whose size |size| is the maximum of |sizeA| and |sizeB|.
     1. [=map/For each=] |index| in [=the range=] 0 to |size|, exclusive:
-       1. Set |shape|[|index|] to the maximum of |shapeA|[|index|] and |shapeB|[|index|].
+        1. Set |shape|[|index|] to the maximum of |shapeA|[|index|] and |shapeB|[|index|].
     1. Return |shape|.
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