docs(fix[tools]): Correct stale tool examples that teach wrong API

why: Docs taught wrong parameters/responses for 3 tools, causing agents
to generate invalid tool calls.
what:
- Remove nonexistent `attach` parameter from create_session side effects
- Fix kill_server response: "Server killed" → "Server killed successfully"
- Fix kill_window example: session_name+window_name → window_id
- Fix kill_window response: window name → window ID

Author: tony

docs/tools/sessions.md

@@ -86,7 +86,7 @@ container — create one before creating windows or panes.
 **Avoid when** a session with the target name already exists — check with
 {tooliconl}`list-sessions` first, or the command will fail.
 
-**Side effects:** Creates a new tmux session. Attaches if `attach` is true.
+**Side effects:** Creates a new tmux session with one window and one pane.
 
 **Example:**
 
@@ -206,7 +206,7 @@ session, window, and pane.
 Response (string):
 
 ```text
-Server killed
+Server killed successfully
 ```
 
 ```{fastmcp-tool-input} server_tools.kill_server

docs/tools/windows.md

@@ -343,16 +343,15 @@ Response:
 {
   "tool": "kill_window",
   "arguments": {
-    "session_name": "dev",
-    "window_name": "old-logs"
+    "window_id": "@1"
   }
 }
 ```
 
 Response (string):
 
 ```text
-Window killed: old-logs
+Window killed: @1
 ```
 
 ```{fastmcp-tool-input} window_tools.kill_window