Update after grammar correct

docs/index.html

@@ -45,7 +45,7 @@
 <li>
 <a href='#tool-management'>Tool management</a></li>
 <li>
-<a href='#usefull-tools'>Usefull tools</a></li>
+<a href='#useful-tools'>Useful tools</a></li>
 </ul>
 </li>
 <li>
@@ -1558,7 +1558,7 @@ <h2 id="tool-management">Tool management</h2>
 <li>Update a globaly installed tool: <code>dotnet tool update -g [tool Name]</code></li>
 </ul>
 <p>Globaly means that the tool is installed to the users profile, instead of the current project/solution.</p>
-<h2 id="usefull-tools">Usefull tools</h2>
+<h2 id="useful-tools">Useful tools</h2>
 <ul>
 <li><p><strong>dotnet-ef</strong></p>
 <p>The command-line interface (CLI) tools for Entity Framework Core perform design-time development tasks. For example, they create migrations, apply migrations, and generate code for a model based on an existing database. The commands are an extension to the cross-platform dotnet command, which is part of the .NET Core SDK. These tools work with .NET Core projects.</p>