filter: add whitelist filter

Fixes: https://github.com/damus-io/noteguard/issues/3
Signed-off-by: William Casarin <jb55@jb55.com>

README.md

@@ -14,12 +14,15 @@ You can add any new filter you want by implementing the `NoteFilter` trait and r
 The `pipeline` config specifies the order in which filters are run. When the first `reject` or `shadowReject` action is hit, then the pipeline stops and returns the rejection error.
 
 ```toml
-
-pipeline = ["ratelimit"]
+pipeline = ["whitelist", "ratelimit"]
 
 [filters.ratelimit]
-notes_per_minute = 8
+posts_per_minute = 8
 whitelist = ["127.0.0.1"]
+
+[filters.whitelist]
+#pubkeys = ["32e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67eef3d9fd9c5c68e245"]
+ips = ["127.0.0.1", "127.0.0.2"]
 ```
 
 ## Filters
@@ -38,6 +41,16 @@ Settings:
 
 - `whitelist`: a list of IP4 or IP6 addresses that are allowed to bypass the ratelimit.
 
+## Whitelist
+
+The whitelist filter only allows notes to pass if it matches a particular pubkey or source ip:
+
+- `pubkeys`: a list of hex public keys to let through
+
+- `ips`: a list of ip addresses to let through
+
+Either criteria can match
+
 ## Testing
 
 You can test your filters like so: