remove inexistent find_custom and rfind_custom functions from Array section

[aziomo]

changelog:

• removed find_custom method from the Array section
• removed rfind_custom method from the Array section

for cleanup reasons, Array class does not have those methods as of 4.4.dev2

why is this in the docs? aside from community requests, there is not even a hint of this feature

[AThousandShips]

This is incorrect, these methods exist in the latest version, they were added in:

• Add callable support for find and rfind Array methods godot#95449

Also these are generated from the source and shouldn't be edited here (see at the top)

Thank you for your contribution nonetheless