Update aws-public-blockchain.yaml

Whitespace fix - yaml

Author: evertonfraga

datasets/aws-public-blockchain.yaml

@@ -2,7 +2,7 @@ Name: AWS Public Blockchain Data
 Description: > 
   <p>The AWS Public Blockchain Data initiative provides free access to blockchain datasets through collaboration with data providers. The data is optimized for analytics by being transformed into compressed Parquet files, partitioned by date for efficient querying.</p>
 
-<h4>Datasets</h4>
+  <h4>Datasets</h4>
   <table width="100%">
   <thead>
     <tr><th>Blockchain dataset</th><th>Maintained by</th><th>Path</th></tr>