[wp-docs] Link(s) to Codex

[Moshu]

Now the Codex is more and more complex, i.e. having the answer for the
majority of newbie questions, I think it would be a good idea to
change the links in the different WP files that point to the support
forum for help - with links that lead to the Codex.

Many times new users come to the forum with questions for which the
only possible answer is to provide a URI to the Codex. And the nature
of the questions tells they have never been there. So, why waste
energy, space, time? Direct them to the Codex first!

just my 2c

moshu