Where are the 9335 to 9400 release notes?

Where are the 9335 to 9400 release notes?

Hi, Looking to upgrade from 9335 to 9400 and/or 9400+hotfixes but the downloads section only starts at 9400 to higher versions.  

Trying to find release notes for upgrading from 9335 to 9400 is impossible and painful.  Dare say they are tucked away somewhere but are they easy to find!......!!!!  

Happy to be proved an idiot, as long as someone shows me the organised links to the info. 

Cheers

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