[keycloak-dev] Social updates and documentation

I've done some updates to social login: * Moved instructions for configuring providers from admin console to documentation * Updated Google provider * Updated/fixed instructions for all providers The reason for all these changes was the other day I tried to enable social login and neither of the providers we have worked. It turns out that Google has changed their console and apis. Facebook had changed its console. Finally, Twitter hadn't changed console or apis, but now requires all traffic to be over https (making it more difficult to test during development). The lesson learned IMO, is: 1) Use Keycloak to enable social login - otherwise you have to muck about this yourself 2) We need to automate testing of the social providers - doing this manually is a real PITA