Remove unnecessary capturing group in suggested rewrite rule

It's not used, nor needed.

doc/usage.rst

@@ -29,7 +29,7 @@ are using apache you can use a ``.htaccess`` file for this.
         RewriteEngine On
         #RewriteBase /path/to/app
         RewriteCond %{REQUEST_FILENAME} !-f
-        RewriteRule ^(.*)$ index.php [QSA,L]
+        RewriteRule ^ index.php [QSA,L]
     </IfModule>
 
 .. note::