dead Northeast Scala Symposium links

[SethTisue]

htmlproofer says:

* At ./_site/pastevents/index.html:280:

  External link https://nescala.io/2011/index.html failed (status code 410)

* At ./_site/pastevents/index.html:4[13](https://github.com/scala/scala-lang/actions/runs/4727082505/jobs/8387302448#step:6:14):

  External link https://nescala.io/2012/index.html failed (status code 410)

* At ./_site/pastevents/index.html:557:

  External link https://nescala.io/2013/index.html failed (status code 410)

* At ./_site/pastevents/index.html:3084:

  External link https://nescala.io/20[17](https://github.com/scala/scala-lang/actions/runs/4727082505/jobs/8387302448#step:6:18)/index.html failed (status code 410)

* At ./_site/pastevents/index.html:3802:

  External link https://nescala.io/20[18](https://github.com/scala/scala-lang/actions/runs/4727082505/jobs/8387302448#step:6:19)/index.html failed (status code 410)

"The domain name nescala.io is for sale"

fyi @jducoeur

[jducoeur]

Yeah, this one's a pure mea culpa - before I got my act together and started to actually organize 2023, a domain squatter got to the domain, somewhere around 4-6 months ago. My current plan is to set up a redirect under sca.la as the hopefully-permanent address, and then we can figure out what that really points to.

Hadn't realized there were historical links from here to older NE Scalas; we'll have to figure out how to stand those up somewhere else. I've added a matching issue in the NE Scala tracker: nescalas/nescala-2023-planning#12

Thanks for calling this to my attention!

[SethTisue]

for now, #1493 replaces the dead links with links to https://twitter.com/nescalas