Remove heading form installation `inc.md` file (#20697)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

docs/getting_started/installation/cpu/apple.inc.md

@@ -35,23 +35,22 @@ pip install -e .
 !!! note
     On macOS the `VLLM_TARGET_DEVICE` is automatically set to `cpu`, which currently is the only supported device.
 
-#### Troubleshooting
-
-If the build has error like the following snippet where standard C++ headers cannot be found, try to remove and reinstall your
-[Command Line Tools for Xcode](https://developer.apple.com/download/all/).
-
-```text
-[...] fatal error: 'map' file not found
-          1 | #include <map>
-            |          ^~~~~
-      1 error generated.
-      [2/8] Building CXX object CMakeFiles/_C.dir/csrc/cpu/pos_encoding.cpp.o
-
-[...] fatal error: 'cstddef' file not found
-         10 | #include <cstddef>
-            |          ^~~~~~~~~
-      1 error generated.
-```
+!!! example "Troubleshooting"
+    If the build has error like the following snippet where standard C++ headers cannot be found, try to remove and reinstall your
+    [Command Line Tools for Xcode](https://developer.apple.com/download/all/).
+
+    ```text
+    [...] fatal error: 'map' file not found
+            1 | #include <map>
+                |          ^~~~~
+        1 error generated.
+        [2/8] Building CXX object CMakeFiles/_C.dir/csrc/cpu/pos_encoding.cpp.o
+
+    [...] fatal error: 'cstddef' file not found
+            10 | #include <cstddef>
+                |          ^~~~~~~~~
+        1 error generated.
+    ```
 
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