Added SDL_HINT_LOGGING documentation to the logging category page.

Fixes https://github.com/libsdl-org/SDL/issues/10335

include/SDL3/SDL_log.h

@@ -29,9 +29,23 @@
  * it will only be sent out if it has that minimum priority or higher.
  *
  * SDL's own logs are sent below the default priority threshold, so they are
- * quiet by default. If you're debugging SDL you might want:
+ * quiet by default.
  *
- * SDL_SetLogPriorities(SDL_LOG_PRIORITY_WARN);
+ * You can change the log verbosity programmatically using SDL_SetLogPriority() or with SDL_SetHint(SDL_HINT_LOGGING, ...), or with the "SDL_LOGGING" environment variable. This variable is a comma separated set of category=level tokens that define the default logging levels for SDL applications.
+ *
+ * The category can be a numeric category, one of "app", "error", "assert",
+ * "system", "audio", "video", "render", "input", "test", or `*` for any
+ * unspecified category.
+ *
+ * The level can be a numeric level, one of "verbose", "debug", "info",
+ * "warn", "error", "critical", or "quiet" to disable that category.
+ *
+ * You can omit the category if you want to set the logging level for all
+ * categories.
+ *
+ * If this hint isn't set, the default log levels are equivalent to:
+ *
+ * `app=info,assert=warn,test=verbose,*=error`
  *
  * Here's where the messages go on different platforms:
  *