Slight change to nipals documentation

[Former user]

In the details section of the nipals documentation, could you add something like this:

For a complete-data matrix X, the NIPALS algorithm returns eig, t, p, where X = t * diag(eig) * t(p).

[Kim-Anh Le Cao]

thanks, this has been pushed to 6.3.1 and we are ready for submission. Many thanks for your contribution!