Improve grammar.

Author: niels-bom-md

basic/index.html

@@ -728,7 +728,7 @@ <h4 id="reset-hard">
        directory look like the index, unstage files and undo any changes made
        since the last commit.
        This is the most dangerous option and not working directory safe. Any
-       changes not in the index or have not been commited will be lost.</p>
+       changes that are not in the index or that have not been commited will be lost.</p>
 
 <pre>
 <b>$ git status</b>