Fix binary example

Signed-off-by: Fabio José <[email protected]>

Author: fabiojose

examples/express-ex/README.md

@@ -23,11 +23,11 @@ __A Binary One__
 curl -X POST \
      -d'@../payload/data-0.json' \
      -H'Content-Type:application/json' \
-     -H'ce_specversion:0.2' \
-     -H'ce_type:com.github.pull.create' \
-     -H'ce_source:https://github.com/cloudevents/spec/pull/123' \
-     -H'ce_id:45c83279-c8a1-4db6-a703-b3768db93887' \
-     -H'ce_time:2019-06-21T17:31:00Z' \
+     -H'ce-specversion:0.2' \
+     -H'ce-type:com.github.pull.create' \
+     -H'ce-source:https://github.com/cloudevents/spec/pull/123' \
+     -H'ce-id:45c83279-c8a1-4db6-a703-b3768db93887' \
+     -H'ce-time:2019-06-21T17:31:00Z' \
      http://localhost:3000/
 ```
 __A Batch One__