Fix raw block Accept header

Author: dirkmc

http-retrieval/README.md

@@ -35,7 +35,7 @@ curl http://{SP's http retrieval URL}/ipfs/{content ID}/{optional path to resour
 For advanced IPFS and IPLD use cases, you can now retrieve individual blocks by passing an `Accept` header with the `application/vnd.ipld.raw;` format
 
 ```
-curl -H "Accept:application/vnd.ipld.car;" http://{SP's http retrieval URL}/ipfs/bagaSomeBlockCID -o bagaSomeBlockCID
+curl -H "Accept:application/vnd.ipld.raw;" http://{SP's http retrieval URL}/ipfs/bagaSomeBlockCID -o bagaSomeBlockCID
 ```
 
 ## Local Setup