Remove resources/ in favor of brand guidelines page (#885)

Now that https://graphql.org/brand/ exists, this removes a secondary source of truth for these image assets.

Author: leebyron

README.md

@@ -1,6 +1,6 @@
 # GraphQL
 
-<img alt="GraphQL Logo" align="right" src="resources/GraphQL%20Logo.svg" width="15%" />
+<img alt="GraphQL Logo" align="right" src="https://graphql.org/img/logo.svg" width="15%" />
 
 The GraphQL specification is edited in the markdown files found in [`/spec`](./spec)
 the latest release of which is published at https://graphql.github.io/graphql-spec/.