Merged PR 16056: Clarify CreateFiber dwStackSize parameter

Clarify CreateFiber dwStackSize parameter

This is passed through to CreateFiberEx, so copy description from there. The point is that this is the stack commit size, not the stack reserve size. The stack reserve size comes from the process defaults.

I verified this behavior down to Windows NT 3.51.

sdk-api-src/content/winbase/nf-winbase-createfiber.md

@@ -68,7 +68,7 @@ To specify both a commit and reserve stack size, use the
 
 ### -param dwStackSize [in]
 
-The initial size of the stack, in bytes. If this parameter is zero, the new fiber uses the default stack size for the executable. For more information, see <a href="https://docs.microsoft.com/windows/desktop/ProcThread/thread-stack-size">Thread Stack Size</a>.
+The initial committed size of the stack, in bytes. If this parameter is zero, the new fiber uses the default commit stack size for the executable. For more information, see <a href="https://docs.microsoft.com/windows/desktop/ProcThread/thread-stack-size">Thread Stack Size</a>.
 
 
 ### -param lpStartAddress [in]