Update the alignment warnings explanation.

majobara-ms · web-flow · commit 55331549db96 · 2021-06-29T18:50:42.000+09:00
The alignment in Windows SDK headers is used by default settings of /Zp option. For x86, use /zp8; for x64, use /zp16.
Clarified the x64 description, as it was previously only for x86.
diff --git a/docs/build/reference/zp-struct-member-alignment.md b/docs/build/reference/zp-struct-member-alignment.md
@@ -31,7 +31,7 @@ The available packing values are described in the following table:
 Don't use this option unless you have specific alignment requirements.
 
 > [!WARNING]
-> The C/C++ headers in the Windows SDK assume **`/Zp8`** packing internally. Don't change the setting from the default when you include the Windows SDK headers, either by using **`/Zp`** on the command line or by using `#pragma pack`. Otherwise, your application may cause memory corruption at runtime.
+> The C/C++ headers in the Windows SDK assume the platform's default alignment is used. Don't change the setting from the default when you include the Windows SDK headers, either by using **`/Zp`** on the command line or by using `#pragma pack`. Otherwise, your application may cause memory corruption at runtime.
 
 You can also use the [`pack` pragma](../../preprocessor/pack.md) to control structure packing. For more information about alignment, see:
 
