Fix various Doxygen warnings in Haiku book.

- Return tags for methods that don't return anything
- ingroup without matching defgroup
- confusion between ref, a, and link tags (they are not the same)
- missed API changes (BObjectList templated owning, new url
  encode/decode API)
- duplicate defgroup definitions

Change-Id: I94a31b04a10a62e71659522c5ed77098728c0843
Reviewed-on: https://review.haiku-os.org/c/haiku/+/9689
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>

docs/user/book.dox

@@ -117,6 +117,9 @@
 		- BKeyStore
 
 
+	\defgroup device Device Kit
+	\brief The Device Kit provides access to devices such as joysticks and serial ports.
+
 	\defgroup game Game Kit
 	\brief The Game Kit provides classes for producing game sounds and
 		working with full screen apps.
@@ -125,6 +128,10 @@
 	\defgroup interface Interface Kit
 	\brief API for displaying a graphical user interface.
 
+	\defgroup kernel Kernel Kit
+	\brief The Kernel Kit provides low-level APIs mainly of use for writing device drivers and
+		kernel modules.
+
 	\defgroup locale Locale Kit
 	\brief Collection of classes for localizing applications.
 
@@ -565,9 +572,6 @@ snooze_until(time - Latency(), B_SYSTEM_TIMEBASE);
 
 	\defgroup libbe Main C++ library (libbe.so)
 
-
-	\defgroup libroot C and POSIX standard functions and extensions (libroot.so)
-	\brief Implements the C and POSIX standard libraries.
 */
 
 ///// Subgroups /////