added `SUPPORT_STANDARD_FILEIO`

CMake-Build-Options.md

@@ -64,3 +64,4 @@ You must set `CUSTOMIZE_BUILD` to ON in order for many of these options to apply
 |`SUPPORT_FILEFORMAT_TTF`       | Support loading fonts in TTF format | `ON`|
 |`SUPPORT_FILEFORMAT_BDF`       | Support loading fonts in BDF format | `OFF`|
 |`SUPPORT_IMAGE_MANIPULATION`   | Support multiple image editing functions to scale, adjust colors, flip, draw on images, crop... If not defined only three image editing functions supported: ImageFormat(), ImageAlphaMask(), ImageToPOT() | `ON`|
+|`SUPPORT_STANDARD_FILEIO`      | Standard file io library (stdio.h) included. Warning: If off, raylib can't read files | `ON` |