docs: api: Replace hotdoc specific commands with Doxygen specific commands

lib/wp/error.h

@@ -17,21 +17,58 @@ G_BEGIN_DECLS
 /**
  * WP_DOMAIN_LIBRARY:
  *
- * A #GError domain for errors that occurred within the context of the
+ * @file error.c
+ * @struct ErrorCodes
+ * @section error_section Error codes
+ *
+ * @brief Error domain and codes for <a href="https://developer.gnome.org/glib/stable/glib-Error-Reporting.html#GError">
+ * GError</a>
+ *
+ * @b wp_domain_library_quark
+ *
+ * @code
+ * GQuark wp_domain_library_quark ()
+ * @endcode
+ *
+ * @subsection error_enum_subsection Enumerations
+ *
+ * @subsubsection error_enum_subsubsection WpLibraryErrorEnum:
+ *
+ * @brief Error codes that can appear in a 
+ * <a href="https://developer.gnome.org/glib/stable/glib-Error-Reporting.html#GError">GError</a>
+ * when the error domain is [WP_DOMAIN_LIBRARY](@ref error_constants_subsection)
+ *
+ * @b Members:
+ *
+ * @arg `WP_LIBRARY_ERROR_INVARIANT (0) – an invariant check failed; this most likely indicates a programming error`
+ * @arg `WP_LIBRARY_ERROR_INVALID_ARGUMENT (1) – an unexpected/invalid argument was given`
+ * @arg `WP_LIBRARY_ERROR_OPERATION_FAILED (2) – an operation failed`
+ *
+ * @subsection error_constants_subsection Constants
+ *
+ * @b WP_DOMAIN_LIBRARY:
+ *
+ * A <a href="https://developer.gnome.org/glib/stable/glib-Error-Reporting.html#GError">
+ * GError</a> domain for errors that occurred within the context of the
  * WirePlumber library.
+ *
+ * @code
+ * #define WP_DOMAIN_LIBRARY (wp_domain_library_quark ())
+ * @endcode 
  */
 #define WP_DOMAIN_LIBRARY (wp_domain_library_quark ())
 WP_API
 GQuark wp_domain_library_quark (void);
 
-/**
- * WpLibraryErrorEnum:
- * @WP_LIBRARY_ERROR_INVARIANT: an invariant check failed; this most likely
+/*!
+ * @em WP_LIBRARY_ERROR_INVARIANT: an invariant check failed; this most likely
  *    indicates a programming error
- * @WP_LIBRARY_ERROR_INVALID_ARGUMENT: an unexpected/invalid argument was given
- * @WP_LIBRARY_ERROR_OPERATION_FAILED: an operation failed
+ * @em WP_LIBRARY_ERROR_INVALID_ARGUMENT: an unexpected/invalid argument was given
+ * @em WP_LIBRARY_ERROR_OPERATION_FAILED: an operation failed
  *
- * Error codes that can appear in a #GError when the error domain
+ * Error codes that can appear in a 
+ * <a href="https://developer.gnome.org/glib/stable/glib-Error-Reporting.html#GError">
+ * GError</a> when the error domain
  * is %WP_DOMAIN_LIBRARY
  */
 typedef enum {