Added singularity build tutorial

docs/contributing.md

@@ -14,7 +14,7 @@ Contributing is very easy even when you have limited programming knowledge!
 1. All of the posts are located in the `docs` folder, creating new folder inside of it will create a new category in the sidebar. Creating an `.md` or React component (`.jsx`) will create a new post. More on [Docusaurus guides](https://docusaurus.io/docs/category/guides)
 1. To preview how the wiki looks like after you add something to the `docs` folder. You have to make sure you have Node.js and Node Package Manager installed, otherwise you can skip step 3 and 4
     ```
-    npm run dev
+    npm run start
     ```
 1. Add, commit and push all changes
     ```