_content/doc/tutorial: fix vulncheck tutorial links

Fixes golang/go#61663

Change-Id: I46a4c0f74aa8c64b7d1eee73b9533c56f8ef8233
Reviewed-on: https://go-review.googlesource.com/c/website/+/514635
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Suzy Mueller <[email protected]>
Reviewed-by: Brandon Kessler <[email protected]>

Author: suzmue

_content/doc/tutorial/index.html

@@ -77,15 +77,15 @@
     </tr>
     <tr class="DocTable-row">
       <td class="DocTable-cell">
-        <a href="doc/tutorial/govulncheck">Getting started with govulncheck</a>
+        <a href="/doc/tutorial/govulncheck">Getting started with govulncheck</a>
       </td>
       <td class="DocTable-cell">Introduces how to find and fix vulnerabilities
         with govulncheck. Govulncheck reports known vulnerabilities that affect
         Go code.</td>
     </tr>
     <tr class="DocTable-row">
       <td class="DocTable-cell">
-        <a href="doc/tutorial/govulncheck-ide">Find and fix vulnerable dependencies with VS Code Go</a>
+        <a href="/doc/tutorial/govulncheck-ide">Find and fix vulnerable dependencies with VS Code Go</a>
       </td>
       <td class="DocTable-cell">Introduces how to find and fix vulnerable
         dependencies directly from your IDE with VS Code Go and Vim.</td>