Provide concrete guidance on picking a entityID

docs/simplesamlphp-artifact-idp.md

docs/simplesamlphp-authproc.md

docs/simplesamlphp-customauth.md

docs/simplesamlphp-ecp-idp.md

docs/simplesamlphp-googleapps.md

docs/simplesamlphp-hok-idp.md

docs/simplesamlphp-idp.md

docs/simplesamlphp-metadata-extensions-attributes.md

docs/simplesamlphp-metadata-extensions-rpi.md

docs/simplesamlphp-metadata-extensions-ui.md

docs/simplesamlphp-modules.md

docs/simplesamlphp-reference-idp-hosted.md

docs/simplesamlphp-sp.md

modules/multiauth/docs/multiauth.md

modules/saml/docs/sp.md