[NFC] Fix typo in CodeGenerator.rst

The file format on z/OS is called GOFF (Generalized Object File Format),
not GCOFF.

GitOrigin-RevId: 5c9e90f2be2a94924edc24fe36f9a5178600c27e
diff --git a/docs/CodeGenerator.rst b/docs/CodeGenerator.rst
index 27889b1..5fb66c7 100644
--- a/docs/CodeGenerator.rst
+++ b/docs/CodeGenerator.rst
@@ -726,7 +726,7 @@
      ``COFF``            AArch64, ARM, X86
      ``DXContainer``     DirectX
      ``ELF``             AArch64, AMDGPU, ARM, AVR, BPF, CSKY, Hexagon, Lanai, LoongArch, M86k, MSP430, MIPS, PowerPC, RISCV, SPARC, SystemZ, VE, X86
-     ``GCOFF``           SystemZ
+     ``GOFF``            SystemZ
      ``MachO``           AArch64, ARM, X86
      ``SPIR-V``          SPIRV
      ``WASM``            WebAssembly