removed extension word

DOCUMENTATION/content/documentation/index.md

@@ -2258,7 +2258,7 @@ For configuration information, visit the [bash-git-prompt repository](https://gi
 
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 <a name="Install-Dnsutils"></a>
-## Install Dnsutils extension
+## Install Dnsutils
 
 1 - First install `dnsutils` in the Workspace and the PHP-FPM Containers:
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