docs: add letdtcode as a contributor for code (#3429)

* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

---------

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -3548,6 +3548,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "letdtcode",
+      "name": "Thanh Nguyen Duc",
+      "avatar_url": "https://avatars.githubusercontent.com/u/92111552?v=4",
+      "profile": "https://github.com/letdtcode",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 6,

README.md

@@ -6,7 +6,7 @@
 [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
 [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-389-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-390-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 <br/>
@@ -578,6 +578,7 @@ This project is licensed under the terms of the MIT license.
       <td align="center" valign="top" width="16.66%"><a href="https://github.com/yybmion"><img src="https://avatars.githubusercontent.com/u/113106136?v=4?s=100" width="100px;" alt="yoobin_mion"/><br /><sub><b>yoobin_mion</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=yybmion" title="Code">💻</a></td>
       <td align="center" valign="top" width="16.66%"><a href="https://ronodhirsoumik.github.io"><img src="https://avatars.githubusercontent.com/u/46843689?v=4?s=100" width="100px;" alt="Soumik Sarker"/><br /><sub><b>Soumik Sarker</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=ronodhirSoumik" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="16.66%"><a href="https://github.com/naman-sriv"><img src="https://avatars.githubusercontent.com/u/82610773?v=4?s=100" width="100px;" alt="Naman Srivastava"/><br /><sub><b>Naman Srivastava</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=naman-sriv" title="Code">💻</a></td>
+      <td align="center" valign="top" width="16.66%"><a href="https://github.com/letdtcode"><img src="https://avatars.githubusercontent.com/u/92111552?v=4?s=100" width="100px;" alt="Thanh Nguyen Duc"/><br /><sub><b>Thanh Nguyen Duc</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=letdtcode" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>