docs: add mackenco as a contributor for ideas (#287)

Adds @mackenco as a contributor for ideas.

This was requested by JoshuaKGoldberg [in this
comment](#36 (comment))

---------

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

.all-contributorsrc

@@ -30,7 +30,8 @@
       "avatar_url": "https://avatars.githubusercontent.com/u/4284340?v=4",
       "profile": "https://github.com/mackenco",
       "contributions": [
-        "code"
+        "code",
+        "ideas"
       ]
     },
     {

README.md

@@ -393,7 +393,7 @@ See [CODE_OF_CONDUCT.md](./CODE_OF_CONDUCT.md).
 <table>
   <tbody>
     <tr>
-      <td align="center" valign="top" width="14.28%"><a href="https://github.com/mackenco"><img src="https://avatars.githubusercontent.com/u/4284340?v=4?s=100" width="100px;" alt="Colin MacKenzie"/><br /><sub><b>Colin MacKenzie</b></sub></a><br /><a href="https://github.com/JoshuaKGoldberg/console-fail-test/commits?author=mackenco" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/mackenco"><img src="https://avatars.githubusercontent.com/u/4284340?v=4?s=100" width="100px;" alt="Colin MacKenzie"/><br /><sub><b>Colin MacKenzie</b></sub></a><br /><a href="https://github.com/JoshuaKGoldberg/console-fail-test/commits?author=mackenco" title="Code">💻</a> <a href="#ideas-mackenco" title="Ideas, Planning, & Feedback">🤔</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://www.kop.ax/"><img src="https://avatars.githubusercontent.com/u/77674046?v=4?s=100" width="100px;" alt="Dimitri Kopriwa"/><br /><sub><b>Dimitri Kopriwa</b></sub></a><br /><a href="https://github.com/JoshuaKGoldberg/console-fail-test/commits?author=kopax-polyconseil" title="Code">💻</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="#tool-JoshuaKGoldberg" title="Tools">🔧</a> <a href="https://github.com/JoshuaKGoldberg/console-fail-test/commits?author=JoshuaKGoldberg" title="Code">💻</a> <a href="#maintenance-JoshuaKGoldberg" title="Maintenance">🚧</a> <a href="#infra-JoshuaKGoldberg" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/sosukesuzuki"><img src="https://avatars.githubusercontent.com/u/14838850?v=4?s=100" width="100px;" alt="SUZUKI Sosuke"/><br /><sub><b>SUZUKI Sosuke</b></sub></a><br /><a href="https://github.com/JoshuaKGoldberg/console-fail-test/commits?author=sosukesuzuki" title="Code">💻</a></td>