Sync SDL3 header -> wiki

SDL3/README/migration.md

@@ -1425,6 +1425,9 @@ SDL3 attempts to apply consistency to case-insensitive string functions. In SDL2
 
 Please note that the case-folding technique used by SDL3 will not produce correct results for the "Turkish 'I'"; this one letter is a surprisingly hard problem in the Unicode world, and since these functions do not specify the human language in use, we have chosen to ignore this problem.
 
+The following macros have been removed:
+* SDL_TABLESIZE() - use SDL_arraysize() instead
+
 The following functions have been renamed:
 * SDL_strtokr() => SDL_strtok_r()
 

SDL3/SDL_arraysize.md

@@ -10,9 +10,14 @@ Defined in [<SDL3/SDL_stdinc.h>](https://github.com/libsdl-org/SDL/blob/main/inc
 ## Syntax
 
 ```c
-#define SDL_arraysize(array)    (sizeof(array)/sizeof(array[0]))
+#define SDL_arraysize(array) (sizeof(array)/sizeof(array[0]))
 ```
 
+## Remarks
+
+NOTE: This macro double-evaluates the argument, so you should never have
+side effects in the parameter.
+
 ## Version
 
 This macro is available since SDL 3.0.0.