[gedit-list] Wiki: plugins page split for the different gedit versions compatibility

[Sébastien Wilmet <swilmet gnome org>]

Hi gedit plugins developers,

The plugins wiki page was quite huge, it is now split in several pages.  
See the Plugins section on the main gedit page:
https://wiki.gnome.org/Apps/Gedit

For third-party plugins, there are now several pages for the different 
gedit versions compatibility:
https://wiki.gnome.org/Apps/Gedit/ThirdPartyPlugins-v3.0
https://wiki.gnome.org/Apps/Gedit/ThirdPartyPlugins-v3.8
https://wiki.gnome.org/Apps/Gedit/ThirdPartyPlugins-v3.12

v3.0: gedit 3.0 to 3.6
v3.8: gedit 3.8 and 3.10
v3.12: gedit 3.12 and above

With the old big page, plugins have been moved from one version to the 
other. So lots of plugins listed on v3.8 are actually also available for 
v3.0, but were removed from the latter list. With the split pages, you 
can add links to the old versions of your plugins.

If you see broken links, outdated stuff, typos, TODO comments, etc, 
don't hesitate to edit the pages. After all, it's a wiki ;)

Thanks,
Sébastien