Added missing link to the Code of Conduct in the community guidelines… (#12432)

Co-authored-by: Thibaud Colas <thibaudcolas@gmail.com>

CONTRIBUTORS.md

@@ -843,6 +843,7 @@
 * Victoria Ottah
 * Bart Cieliński
 * alexkiro
+* Ankit Kumar
 
 ## Translators
 

docs/contributing/first_contribution_guide.md

@@ -54,7 +54,7 @@ You may also want to join StackOverflow and [follow the Wagtail tag](https://sta
 #### Checklist
 
 ```markdown
--   [ ] Read the community guidelines
+-   [ ] Read the [community guidelines](https://github.com/wagtail/wagtail/blob/main/CODE_OF_CONDUCT.md)
 -   [ ] Join GitHub
 -   [ ] Add your preferred name and image to your GitHub profile
 -   [ ] Join Slack