doc: add doc for 2 win chapters and fix typo in windows dialog

doc/src/windows/com.dox

@@ -0,0 +1,31 @@
+namespace yycc::windows::com {
+/**
+
+\page windows__com COM Helper
+
+This namespace is Windows specific.
+It will be invisible on other platforms.
+
+\section windows__com__memory_safe_ptr Memory Safe Pointer Types
+
+This namespace provides various memory-safe types for interacting with COM functions.
+Although Microsoft also has similar smart pointer called \c CComPtr.
+But this library is eager to hide all Microsoft-related functions calling.
+Using \c CComPtr is not corresponding with the philosophy of this library.
+So these standard library based smart pointer and corresponding deleter types were created.
+
+\section windows__com__com_guard COM Guard
+
+This namespace contains a COM Guard which make sure COM was initialized in current module when loading current module.
+It is essential because all calling to COM functions should be under the premise that COM has been initialized.
+This guard also will uninitialize COM when unloading this module.
+
+There is only an exposed function called is_initialized() for user calling.
+This function will check whether COM environment is initialized.
+If you want YYCC automatically initialize COM environment for you,
+you must call this function in your program at least one time.
+Otherwise COM Guard code may be unavailable,
+because compiler may think these code is not referenced by any other code and drop them.
+
+*/
+}