Fix link for tutor.txt file

usage.html

@@ -139,7 +139,7 @@
                     <main>
                         <h1 id="usage"><a class="header" href="#usage">Usage</a></h1>
 <p>(Currently not fully documented, see the <a href="./keymap.html">keymappings</a> list for more.)</p>
-<p>See <a href="https://github.com/helix-editor/helix/blob/master/runtime/tutor.txt">tutor.txt</a> (accessible via <code>hx --tutor</code> or <code>:tutor</code>) for a vimtutor-like introduction.</p>
+<p>See <a href="https://github.com/helix-editor/helix/blob/22.08.1/runtime/tutor.txt">tutor.txt</a> (accessible via <code>hx --tutor</code> or <code>:tutor</code>) for a vimtutor-like introduction.</p>
 <h2 id="registers"><a class="header" href="#registers">Registers</a></h2>
 <p>Vim-like registers can be used to yank and store text to be pasted later. Usage is similar, with <code>&quot;</code> being used to select a register:</p>
 <ul>