[keycloak-dev] Doc renaming and organization suggestion

I suggest we rename Server Developer Guide to Keycloak (RH-SSO) Developer Guide. We move all programmer related SPIs, REST interface docs (token exchange), Client Registration, adapter SPIs, really anything a developer would do to this guide. Securing Apps should be specifically configuration tasks for securing an application. Only things an admin would do and no developer concerns should be there. -- Bill Burke Red Hat