another grammar fix

Author: GarboMuffin

src/index.html

@@ -165,7 +165,7 @@ <h2>How sb3fix works</h2>
       Depending on how badly the zip is corrupted, sb3fix might recover your project in its entirety or may miss significant parts.
     </p>
     <details>
-      <summary>Example of error messages due to zip corruption</summary>
+      <summary>Examples of error messages due to zip corruption</summary>
       <ul class="error-list">
         <li><code>Corrupted zip: can't find end of central directory</code></li>
         <li><code>Corrupted zip or bug: unexpected signature (\x00\x00\x00\x00, expected \x50\x4B\x03\x04)</code></li>