fix(methods): pass required canvas_id in getCanvas/setCanvasContent examples

Both methods require canvas_id to target a specific canvas.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>

Author: zimeg

methods/src/code_channels/code_channels_get_canvas.py

@@ -11,6 +11,7 @@
 # Call the codeChannels.getCanvas method
 response = client.codeChannels_getCanvas(
     channel_id="C123ABC456",
+    canvas_id="F123ABC456",
 )
 
 # Inspect the response

methods/src/code_channels/code_channels_set_canvas_content.py

@@ -11,6 +11,7 @@
 # Call the codeChannels.setCanvasContent method
 response = client.codeChannels_setCanvasContent(
     channel_id="C123ABC456",
+    canvas_id="F123ABC456",
     content="# Plan\n\n1. Reproduce the flaky test\n2. Fix the race\n3. Verify",
 )