rename Netlify usages by Vercel (graphql#1649)

Author: dimaMachina

CONTRIBUTING.md

@@ -70,7 +70,7 @@ Active development for graphql.org happens on the `source` branch. Be sure to cr
 
 ### Publishing the updated site
 
-Your changes will be merged into the `source` branch. Then, the CI will automatically publish a new version of https://graphql.org via [Netlify](https://docs.netlify.com).
+Your changes will be merged into the `source` branch. Then, the CI will automatically publish a new version of https://graphql.org via [Vercel](https://vercel.com/docs).
 
 ## Updating content
 

README.md

@@ -16,7 +16,7 @@ A brief overview: **GraphQL** is a query language for APIs and a runtime for ful
 
 ## Deployment
 
-The site is deployed via Netlify on merges to the source branch, you can see the [builds here](https://app.netlify.com/teams/graphql-org/builds).
+The site is deployed via Vercel on merges to the `source` branch.
 
 ## How to contribute