Doxygen: document some UTF-8 typedefs

include/rapidjson/rapidjson.h

@@ -265,6 +265,7 @@ struct StreamTraits<GenericStringStream<Encoding> > {
 	enum { copyOptimization = 1 };
 };
 
+//! String stream with UTF8 encoding.
 typedef GenericStringStream<UTF8<> > StringStream;
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -301,6 +302,7 @@ struct StreamTraits<GenericInsituStringStream<Encoding> > {
 	enum { copyOptimization = 1 };
 };
 
+//! Insitu string stream with UTF8 encoding.
 typedef GenericInsituStringStream<UTF8<> > InsituStringStream;
 
 ///////////////////////////////////////////////////////////////////////////////

include/rapidjson/stringbuffer.h

@@ -37,6 +37,7 @@ struct GenericStringBuffer {
 	mutable internal::Stack<Allocator> stack_;
 };
 
+//! String buffer with UTF8 encoding
 typedef GenericStringBuffer<UTF8<> > StringBuffer;
 
 //! Implement specialized version of PutN() with memset() for better performance.