Adding missing function to documentation
Adding missing function to documentation

The function `miopenCreateActivationDescriptor` was missing in the documentation.
ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen,ROCmSoftwarePlatform/MIOpen