Update documentation with new features

docs/1-user-guide.md

@@ -285,6 +285,15 @@ If you want information about a proxied message (eg. for moderation reasons), yo
 Either you can react to the message itself with the ❔ or ❓ emoji, which will DM you information about the message in question, 
 or you can use the `pk;message` command followed by [the message's ID](https://support.discordapp.com/hc/en-us/articles/206346498-Where-can-I-find-my-User-Server-Message-ID-).
 
+### Pinging a specific user
+If you'd like to "ping" the account behind a proxied message without having to query the message and ping them yourself,
+you can react to the message with the 🔔 or ❗ emoji, and PluralKit will ping the relevant member and account in the same
+channel on your behalf with a link to the message you reacted to.
+
+### Disabling proxying on a per-server basis
+If you need to disable proxying messages for your system entirely in a specific server (for example, if you'd like to
+use a different proxy bot there), you can type `pk;system proxy on/off` to do that.
+
 ### Deleting messages
 Since the messages will be posted by PluralKit's webhook, there's no way to delete the message as you would a normal user message.
 To delete a PluralKit-proxied message, you can react to it with the ❌ emoji. Note that this only works if the message has

docs/2-command-list.md

@@ -17,6 +17,7 @@ Words in \<angle brackets> are *required parameters*. Words in [square brackets]
 - `pk;system avatar [avatar url]` - Changes the avatar of your system.
 - `pk;system tag [tag]` - Changes the system tag of your system.
 - `pk;system timezone [location]` - Changes the time zone of your system.
+- `pk;system proxy [on|off]` - Toggles message proxying for a specific server. 
 - `pk;system delete` - Deletes your system.
 - `pk;system [id] fronter` - Shows the current fronter of a system.
 - `pk;system [id] fronthistory` - Shows the last 10 fronters of a system.

docs/3-api-documentation.md

@@ -67,6 +67,7 @@ The following three models (usually represented in JSON format) represent the va
 |---|---|---|
 |timestamp|datetime||
 |id|snowflake|The ID of the message sent by the webhook. Encoded as string for precision reasons.|
+|original|snowflake|The ID of the (now-deleted) message that triggered the proxy. Encoded as string for precision reasons.|
 |sender|snowflake|The user ID of the account that triggered the proxy. Encoded as string for precision reasons.|
 |channel|snowflake|The ID of the channel the message was sent in. Encoded as string for precision reasons.|
 |system|full System object|The system that proxied the message.|
@@ -371,6 +372,7 @@ Queries a system by its linked Discord account ID (17/18-digit numeric snowflake
 
 ### GET /msg/\<id>
 Looks up a proxied message by its message ID. Returns `404 Not Found` if the message ID is invalid or wasn't found (eg. was deleted or not proxied by PK).
+You can also look messages up by their *trigger* message ID (useful for, say, logging bot integration).
 
 #### Example request
     GET https://api.pluralkit.me/v1/msg/601014599386398700
@@ -380,6 +382,7 @@ Looks up a proxied message by its message ID. Returns `404 Not Found` if the mes
 {
     "timestamp": "2019-07-17T11:37:26.805Z",
     "id": "601014599386398700",
+    "original": "601014598168435600",
     "sender": "466378653216014359",
     "channel": "471388251102380000",
     "system": {