Fix minor typo in index.html (#1787)

Author: ravicodelabs

index.html

@@ -123,7 +123,7 @@ <h4>Functional programming</h4>
     <h4>Extensibility and DSLs</h4>
 
     <div class="entry-summary">
-      <p>Elixir has been designed to be extensible, allowing developers naturally extend the language to particular domains, in order to increase their productivity.</p>
+      <p>Elixir has been designed to be extensible, allowing developers to naturally extend the language to particular domains, in order to increase their productivity.</p>
 
       <p>As an example, let's write a simple test case using <a href="https://hexdocs.pm/ex_unit/">Elixir's test framework called ExUnit</a>:</p>