change all iesg meeting minute index page slugs to use only years

[ghwood]

URL

e.g. https://beta.ietf.org/about/groups/iesg/minutes/iesg-minutes-2016/

Expected Behavior

https://beta.ietf.org/about/groups/iesg/minutes/2016/

Actual Behavior

(include a screen shot if you like)

Reproducing

• Browser:
• OS: [Operating System name] [Version]
• (anything else you think we might need to reproduce this)

[ghwood]

blocked by #72

[ghwood]

This is fixed.