[droid] add a bit of doxy to AndroidAppFile so it's clear what it's for

xbmc/filesystem/AndroidAppFile.h

@@ -31,20 +31,25 @@ namespace XFILE
 class CFileAndroidApp : public IFile
 {
 public:
+  /*! \brief Currently only used for retrieving App Icons. */
   CFileAndroidApp(void);
   virtual ~CFileAndroidApp(void);
   virtual bool Open(const CURL& url);
   virtual bool Exists(const CURL& url);
   virtual int Stat(const CURL& url, struct __stat64* buffer);
 
+  /*! \brief Return 32bit rgba raw bitmap. */
   virtual unsigned int Read(void* lpBuf, int64_t uiBufSize);
   virtual void Close();
   virtual int64_t GetLength();
   virtual int64_t Seek(int64_t, int) {return -1;};
   virtual int64_t GetPosition() {return 0;};
   virtual int GetChunkSize();
   virtual int IoControl(EIoControl request, void* param);
+
+  /*! \brief Only valid after GetLength() has been called, usually by Open(). */
   unsigned int GetIconWidth();
+  /*! \brief Only valid after GetLength() has been called, usually by Open(). */
   unsigned int GetIconHeight();
 
 protected: