Assuming in First Network setup, go to the CLI container.
docker exec -it cli bash
The CLI default will access peer0.org1.example.com. Then you can fetch a block either newest, or specifying the block number (reference).
peer channel fetch newest | (number)
You will get back a file in pb format. Finally you can decode it into JSON such that you can read it (reference).
configtxlator proto_decode --type=common.Block --input <pb_file> --output <json_file>
The file is still inside CLI container. You can
docker cp it to localhost for easy reading.
You can locate endorsement in the JSON file, in which you can see the endorsers, their signatures, and the RWSet.
HTH… cheers, kc