Add a community for international/exchange students to Communities

Communities now has identity- and subject-focused spaces (I'm First for first-generation students, AnitaB.org and oSTEM (#205) for tech, several Reddit and Stack Exchange communities), but nothing for international or exchange students navigating a new country's academic and social systems specifically, a distinct experience from Gap Year & Study Abroad's logistics-focused resources. Add 1 reputable, free community or forum for international/exchange students, following the format in CONTRIBUTING.md. Scope: about 15-20 minutes.