"current" URL/link for Octave docs

[Andrew Janke]

Hi, Octave maintainers,

Whenever I google for Octave documentation, it picks up the old 4.2.1
release. E.g. googling for "octave loglog" gets me
https://octave.org/doc/v4.2.1/Two_002dDimensional-Plots.html. And when
I'm sharing links to Octave doco, I often don't want a particular
release; just the "latest and greatest".

What do you think about making a https://octave.org/doc/current link to
the latest stable version's doco? Then we could link to
latest-and-greatest. And over time, maybe that would acquire enough
googlejuice that it would become the top results for Octave doco
searches, so people would find the current docs when searching?

Cheers,
Andrew