[examples] Typo in comment of example Textures Image Generation

[Logicless-Coder]

Issue:
As visible in the line referenced below, there is a grammatical error in the comment of the example textures/textures_image_generation

raylib/examples/textures/textures_image_generation.c

Line 16 in 2361615

#define NUM_TEXTURES 9 // Currently we have 8 generation algorithms but some are have multiple purposes (Linear and Square Gradients)

Resolution:
Instead of ... but some are have multiple purposes ... it should be ... but some have multiple purposes ..., hence "are" should be removed.

[Logicless-Coder]

Implemented the fix as #3817