Update index.md
Update index.md

Add note re Linux/OS X being the only supported hosts at present (refs #62)
Add note re current need to use HTTP/HTTPS rather than unix sockets (refs #61)
rnorth/test-containers,testcontainers/testcontainers-java,gorelikov/testcontainers-java,outofcoffee/testcontainers-java,barrycommins/testcontainers-java,outofcoffee/testcontainers-java,barrycommins/testcontainers-java,testcontainers/testcontainers-java,gorelikov/testcontainers-java,gorelikov/testcontainers-java,barrycommins/testcontainers-java,barrycommins/testcontainers-java,rnorth/test-containers,rnorth/test-containers,gorelikov/testcontainers-java,testcontainers/testcontainers-java,outofcoffee/testcontainers-java