Tweak refcard note about documentation location

Tweak refcard note about documentation location

* etc/refcards/calccard.tex, etc/refcards/cs-dired-ref.tex:
* etc/refcards/cs-refcard.tex, etc/refcards/cs-survival.tex:
* etc/refcards/de-refcard.tex, etc/refcards/dired-ref.tex:
* etc/refcards/fr-dired-ref.tex, etc/refcards/fr-refcard.tex:
* etc/refcards/fr-survival.tex, etc/refcards/gnus-refcard.tex:
* etc/refcards/orgcard.tex, etc/refcards/pl-refcard.tex:
* etc/refcards/pt-br-refcard.tex, etc/refcards/refcard.tex:
* etc/refcards/ru-refcard.tex, etc/refcards/sk-dired-ref.tex:
* etc/refcards/sk-refcard.tex, etc/refcards/sk-survival.tex:
* etc/refcards/survival.tex, etc/refcards/vipcard.tex:
* etc/refcards/viperCard.tex: Tweak documentation url.