readme: describe the format
## Quickstart
+Root privilege is required to interact with the BPF virtual machine.
+The format is: `ConnID ReqID HeaderName HeaderValue`, except the first line that represents the HTTP protocol version.
+
```
$ sudo h2olog -p $(pgrep -o h2o)
@@ -15,8 +18,6 @@ $ sudo h2olog -p $(pgrep -o h2o)
... and more ...
```
-Root privilege is required to interact with the BPF virtual machine.
-
## Requirements
- H2O server built after [886db137](https://github.com/h2o/h2o/pull/2057/commits/886db13791bb03794901710974fb52cd1238968e)
