Update further translatable inkscape.org links to https

Currently in inkscape.pot file there are several translatable links to inkscape.org:

1. https://inkscape.org/en/learn/faq#dpi_change
2. https://inkscape.org/learn/tutorials/
3. https://inkscape.org/en/ask/
4. http://inkscape.org/doc/inkscape-man.html
5. http://inkscape.org/doc/keys092.html
6. http://wiki.inkscape.org/wiki/index.php/Release_notes/1.0

I updated 4. and 5. to HTTPS in this merge request. Wiki is HTTP link too, but there are no certificate.

As translator I suggest to update all links to include language prefix (as currently 1. and 3.). This way it would be clear, what should I translate:

• 2. https://inkscape.org/en/learn/tutorials/
• 4. https://inkscape.org/en/doc/inkscape-man.html
• 5. https://inkscape.org/en/doc/keys092.html

If you agree, I will update this merge request.