Update .CONTRIBUTING.md

Co-authored-by: Erin Shaben <[email protected]>

Author: brunopgalvao

.CONTRIBUTING.md

@@ -55,7 +55,7 @@ For more complex contributions, which involve rendering (e.g., adding a `.Nav` s
 
 Before making contributions, you need to set up the proper directory structure for local development:
 
-1. **Clone the MkDocs repository**
+1. Clone the MkDocs repository:
 
    > **polkadot-mkdocs**: Contains the "engine" (MkDocs configuration, theme, styling)