Fix typo in bash helper example

Author: JoshuaBehrens

external/book/content/book/en/v2/Git-Tools-Credential-Storage.html

@@ -170,7 +170,7 @@ <h3 id="_under_the_hood">Under the Hood</h3>
 <td class="tableblock halign-left valign-top"><p class="tableblock">Runs <code>/absolute/path/foo -xyz</code></p></td>
 </tr>
 <tr>
-<td class="tableblock halign-left valign-top"><p class="tableblock"><code>!f() { echo "password=s3cre7"; }; f</code></p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock"><code>! if() { echo "password=s3cre7"; };</code></p></td>
 <td class="tableblock halign-left valign-top"><p class="tableblock">Code after <code>!</code> evaluated in shell</p></td>
 </tr>
 </tbody>
@@ -355,4 +355,4 @@ <h3 id="_a_custom_credential_cache">A Custom Credential Cache</h3>
 <p>As you can see, extending this system is pretty straightforward, and can solve some common problems for you and your team.</p>
 </div>
 </div>
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+<div id="nav"><a href="{{< previous-section >}}">prev</a> | <a href="{{< next-section >}}">next</a></div>