[Mageia-i18n] Complete the .lang files list for the Greek language

[Filip Komar]

Hi Dimitrios and others. I switched Greek pages values and
code-of-conduct from html to lang system[1] as they already existed
before. Please check the result.

I have also added some instructions about such cases in our wiki[2]. I
would be glad if someone can comment on that. Especially if
instructions are clearly understandable.

Have a nice weekend,
Filip.


[1] http://svnweb.mageia.org/web?view=revision&revision=1722
[2] https://wiki.mageia.org/en/Internationalisation_Team_(i18n)#Website_translation