Change Volunteer Signup from Google Form to Direct List Sign Up

[annalorimer]

Problem:

• Currently we are linking to a Google Form for people to use to sign up for volunteering
• This means that we have to copy over the email addresses to the mailing list which causes mistakes

Solution:

• Link to https://lists.uwaterloo.ca/mailman/listinfo/wics-volunteers instead

[annalorimer]

Oops this is a duplicate of #249