docs: add mvanhorn as a contributor for code (#121)

* docs: update README.md

* docs: update .all-contributorsrc

---------

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>

Author: allcontributors[bot]

.all-contributorsrc

@@ -1,4 +1,21 @@
 {
   "projectName": "gh-stack",
-  "projectOwner": "boneskull"
+  "projectOwner": "boneskull",
+  "files": [
+    "README.md"
+  ],
+  "commitType": "docs",
+  "commitConvention": "angular",
+  "contributorsPerLine": 7,
+  "contributors": [
+    {
+      "login": "mvanhorn",
+      "name": "Matt Van Horn",
+      "avatar_url": "https://avatars.githubusercontent.com/u/455140?v=4",
+      "profile": "https://github.com/mvanhorn",
+      "contributions": [
+        "code"
+      ]
+    }
+  ]
 }

README.md

@@ -490,6 +490,13 @@ See [ARCHITECTURE.md](ARCHITECTURE.md) for a detailed breakdown of **gh-stack**'
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
 <!-- prettier-ignore-start -->
 <!-- markdownlint-disable -->
+<table>
+  <tbody>
+    <tr>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/mvanhorn"><img src="https://avatars.githubusercontent.com/u/455140?v=4?s=100" width="100px;" alt="Matt Van Horn"/><br /><sub><b>Matt Van Horn</b></sub></a><br /><a href="#code-mvanhorn" title="Code">💻</a></td>
+    </tr>
+  </tbody>
+</table>
 
 <!-- markdownlint-restore -->
 <!-- prettier-ignore-end -->