Update mod-reference.md

Migrated `https://wiki.beammp.com/en/Scripting/client_scripting` from the wiki.

docs/en/scripting/mod-reference.md

@@ -7,3 +7,37 @@
     This can be done any page too.
 
 # Mod/In-Game Scripting Reference
+
+BeamMP allows you to create your own client side plugins as well. We have provided a few functions that you can use to communicate with other multiplayer mods, and other players through the server.
+
+# Functions
+
+List of available functions for scripting:
+
+| Function                                  | Notes                                                                                                                                                                                 |
+|-------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `TriggerServerEvent("eventName", "data")` | Triggers an event in the server lua environment, both parameters are strings.                                                                                                         |
+| `TriggerClientEvent("eventName", "data")` | Triggers an event in the local lua environment, both parameters are strings. Good for communication between plugins.                                                                  |
+| `AddEventHandler("eventName", Function)`  | Adds the 2nd parameter to the table to be called when eventName is received (either locally or from the server), `Function` will get 1 parameter, a string containing the event data. |
+
+# Code snippets
+
+For example to parse the chat use the included `ChatMessageIncluded` event as such:
+
+```lua
+local function chatReceived(msg) -- Receive event with parameters
+    print("chat received: "..msg)
+    local i = string.find(s, ":") -- Find where our first ':' is, used to separate the sender and message
+    if i == nil then
+        print("error parsing message: separator could not be found!")
+        return -- Could not find separator, cancel function
+    end
+    print("index of separator: "..tostring(i))
+    local sender = string.sub(msg, 1, i-1) -- Substring our input to separate its 2 parts
+    local message = string.sub(msg, i+1, -1)  -- Do whatever you want to with the message
+    print("sender: " .. sender)
+    print("message: ".. message)
+end
+
+AddEventHandler("ChatMessageReceived", chatReceived) -- Add our event handler to the list managed by BeamMP
+```