update BUGS links

[bob-carpenter]

Now on a blog.

See: #122

[mitzimorris]

links to WinBUGS examples are good, but links to OpenBUGS return "bad gateway" error
and cannot find any other site where these models can be found.

[mitzimorris]

found a copy here:

http://pj.freefaculty.org/Ubuntu/15.04/amd64/openbugs/openbugs-3.2.3/debian/openbugs/usr/share/doc/openbugs-3.2.3/Examples/Volumei.html

http://pj.freefaculty.org/Ubuntu/15.04/amd64/openbugs/openbugs-3.2.3/debian/openbugs/usr/share/doc/openbugs-3.2.3/Examples/Volumeii.html

http://pj.freefaculty.org/Ubuntu/15.04/amd64/openbugs/openbugs-3.2.3/debian/openbugs/usr/share/doc/openbugs-3.2.3/Examples/Volumeiii.html

[mitzimorris]

link to GitHub mirror ?

https://github.com/jsta/openbugs/tree/master/doc/Examples