fix(lint): make markdown linter happy

Author: bdeneux

docs/index.md

@@ -49,7 +49,6 @@ Welcome! OKP4 is a public PoS layer 1 blockchain built for trust-minimized data
   </div>
 </div>
 
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 ## Learn OKP4 concepts
 
 <div class="docs-card-container">
@@ -189,7 +188,6 @@ Welcome! OKP4 is a public PoS layer 1 blockchain built for trust-minimized data
   </div>
 </div>
 
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 Welcome to the OKP4 community! Find out more about us at:
 
 * [Website](https://okp4.network/)