review: document peer_type.

Signed-off-by: Piotr Sikora <[email protected]>

Author: PiotrSikora

abi-versions/v0.2.1/README.md

@@ -898,6 +898,9 @@ Plugin must return one of the following values:
 
 Called when downstream connection is closed.
 
+The `peer_type` should describe whether this was initiated by a `LOCAL`
+or `REMOTE` peer, but this value might also be `UNKNOWN`.
+
 
 #### `proxy_on_upstream_data`
 
@@ -938,6 +941,9 @@ Plugin must return one of the following values:
 
 Called when upstream connection is closed.
 
+The `peer_type` should describe whether this was initiated by a `LOCAL`
+or `REMOTE` peer, but this value might also be `UNKNOWN`.
+
 
 ## HTTP streams