Log Message:
Update gnome-devel-docs to 2.26.0.

Version 2.26.0
--------------
* Human Interface Guidelines:
  - Fixed an image to match text (Calum Benson)
  - Validity fixes (Shaun McCance)
* Integration Guide:
  - Minor fixes (Leonardo Ferreira Fontenelle, Federico Mena Quintero)
  - Updated translations:
    cs      (Lucas Lommer)
    en_GB   (Jen Ockwell)
    es      (Jorge Gonzalez)
    pt_BR   (Leonardo Ferreira Fontenelle)
    sv      (Daniel Nylander)
* Platform Overview:
  - Fixed some links to freedesktop.org specs, bug #558800 (Shaun McCance)
  - Updated cvs.gnome.org to svn.gnome.org, bug #566039 (Adam Dingle)
  - Various typo corrections
  - Updated translations:
    es      (Jorge Gonzalez)
    fr      (Frederic Peters)
    ru      (Nikita Belobrov)
* Accessibility Devel Guide:
  - Various updates