I've written a lot of software documentation and even authored a few style guides.
I would not suggest using his/her throughout the text. In the generic case, refer to the user as "they", which serves as a somewhat suitable gender-neutral pronoun if you use it intermittently. Try to to strike a good mix between "the user" and "they." Using one over the other consistently starts to sound redundant and somewhat forced.
The user enters text and clicks 'done'. They have the option of saving to a file or the network.
Another option you may consider is changing the voice to the second person ("you") in parts of the document (or even the entire text). Talk to them directly. Put them in the use cases.
Enter the text and click 'done'. You can save the text to a file or the network.