AMDGPU/Docs: Add links to instruction descriptions for gfx941, gfx942 (llvm#70941)

Co-authored-by: Konstantin Zhuravlyov <[email protected]>

Author: kzhuravl

llvm/docs/AMDGPUUsage.rst

@@ -14745,6 +14745,10 @@ in this description.
 
     CDNA 3        :doc:`GFX9<AMDGPU/AMDGPUAsmGFX9>`             :doc:`gfx940<AMDGPU/AMDGPUAsmGFX940>`
 
+                                                                :doc:`gfx941<AMDGPU/AMDGPUAsmGFX940>`
+
+                                                                :doc:`gfx942<AMDGPU/AMDGPUAsmGFX940>`
+
     RDNA 1        :doc:`GFX10 RDNA1<AMDGPU/AMDGPUAsmGFX10>`     :doc:`gfx1010<AMDGPU/AMDGPUAsmGFX10>`
 
                                                                 :doc:`gfx1011<AMDGPU/AMDGPUAsmGFX1011>`