docs: add JoshuaKGoldberg as a contributor for code (#527)

Adds @JoshuaKGoldberg as a contributor for code.

This was requested by lwasser [in this
comment](#508 (comment))

[skip ci]

---------

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -263,7 +263,8 @@
       "avatar_url": "https://avatars.githubusercontent.com/u/3335181?v=4",
       "profile": "http://www.joshuakgoldberg.com",
       "contributions": [
-        "bug"
+        "bug",
+        "code"
       ]
     },
     {

README.md

@@ -93,7 +93,7 @@ Thanks goes to these wonderful people ([emoji key](https://github.com/all-contri
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/KnorpelSenf"><img src="https://avatars.githubusercontent.com/u/12952387?v=4?s=100" width="100px;" alt="KnorpelSenf"/><br /><sub><b>KnorpelSenf</b></sub></a><br /><a href="https://github.com/all-contributors/app/commits?author=KnorpelSenf" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://chjh.nl"><img src="https://avatars.githubusercontent.com/u/2946344?v=4?s=100" width="100px;" alt="Chris Hartgerink"/><br /><sub><b>Chris Hartgerink</b></sub></a><br /><a href="https://github.com/all-contributors/app/commits?author=chartgerink" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="http://linkedin.com/in/tbueschel"><img src="https://avatars.githubusercontent.com/u/13087421?v=4?s=100" width="100px;" alt="Tobias Büschel"/><br /><sub><b>Tobias Büschel</b></sub></a><br /><a href="https://github.com/all-contributors/app/commits?author=tobiasbueschel" title="Code">💻</a> <a href="https://github.com/all-contributors/app/commits?author=tobiasbueschel" title="Tests">⚠️</a></td>
-      <td align="center" valign="top" width="14.28%"><a href="http://www.joshuakgoldberg.com"><img src="https://avatars.githubusercontent.com/u/3335181?v=4?s=100" width="100px;" alt="Josh Goldberg ✨"/><br /><sub><b>Josh Goldberg ✨</b></sub></a><br /><a href="https://github.com/all-contributors/app/issues?q=author%3AJoshuaKGoldberg" title="Bug reports">🐛</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="http://www.joshuakgoldberg.com"><img src="https://avatars.githubusercontent.com/u/3335181?v=4?s=100" width="100px;" alt="Josh Goldberg ✨"/><br /><sub><b>Josh Goldberg ✨</b></sub></a><br /><a href="https://github.com/all-contributors/app/issues?q=author%3AJoshuaKGoldberg" title="Bug reports">🐛</a> <a href="https://github.com/all-contributors/app/commits?author=JoshuaKGoldberg" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/jpivarski"><img src="https://avatars.githubusercontent.com/u/1852447?v=4?s=100" width="100px;" alt="Jim Pivarski"/><br /><sub><b>Jim Pivarski</b></sub></a><br /><a href="https://github.com/all-contributors/app/issues?q=author%3Ajpivarski" title="Bug reports">🐛</a></td>
     </tr>
     <tr>