include: Add \since to all documentation that was missing it.

include/SDL3/SDL_log.h

@@ -50,6 +50,8 @@ extern "C" {
  * The maximum size of a log message prior to SDL 2.0.24.
  *
  * As of 2.0.24 there is no limit to the length of SDL log messages.
+ *
+ * \since This macro is available since SDL 3.0.0.
  */
 #define SDL_MAX_LOG_MESSAGE 4096
 
@@ -59,6 +61,8 @@ extern "C" {
  * By default the application category is enabled at the INFO level, the
  * assert category is enabled at the WARN level, test is enabled at the
  * VERBOSE level and all other categories are enabled at the ERROR level.
+ *
+ * \since This enum is available since SDL 3.0.0.
  */
 typedef enum SDL_LogCategory
 {
@@ -97,6 +101,8 @@ typedef enum SDL_LogCategory
 
 /**
  * The predefined log priorities
+ *
+ * \since This enum is available since SDL 3.0.0.
  */
 typedef enum SDL_LogPriority
 {
@@ -363,6 +369,8 @@ extern DECLSPEC void SDLCALL SDL_LogMessageV(int category,
  * \param category the category of the message
  * \param priority the priority of the message
  * \param message the message being output
+ *
+ * \since This datatype is available since SDL 3.0.0.
  */
 typedef void (SDLCALL *SDL_LogOutputFunction)(void *userdata, int category, SDL_LogPriority priority, const char *message);