Website: delete broken aria-labeled-by

No #footnote-lsp-not-global element exists. Delete the dangling
aria-labeled-by reference.

Author: strager

website/public/install/index.ejs.html

@@ -561,9 +561,8 @@ <h2>Install quick-lint-js</h2>
             such as documentation or shell completion plugins.
           </p>
           <p>
-            <span aria-labeled-by="footnote-lsp-not-global">**</span> The LSP
-            server is not installed globally with this installation method, so
-            some editors might not be able to access it.
+            <span>**</span> The LSP server is not installed globally with this
+            installation method, so some editors might not be able to access it.
           </p>
         </figcaption>
       </figure>