Resolve #1608 document errors

Author: seratch

docs/content/web.md

@@ -258,7 +258,7 @@ error code).
 response = client.files_upload_v2(
     file="test.pdf",
     title="Test upload",
-    channel_id="C3UKJTQAC",
+    channel="C3UKJTQAC",
     initial_comment="Here is the latest version of the file!",
 )
 ```
@@ -269,7 +269,7 @@ If you want to share files within a thread, you can pass "thread_ts" in addition
 response = client.files_upload_v2(
     file="test.pdf",
     title="Test upload",
-    channel_id="C3UKJTQAC",
+    channel="C3UKJTQAC",
     thread_ts="1731398999.934122",
     initial_comment="Here is the latest version of the file!",
 )