Installation of Istio gateway (Keycloak install.sh) fails due to missing configmap 'global'

[mbert]

After the recent refactoring of the install documentation the section on the configmap global and related information about what it is good for, how to create it correctly etc. was removed (global_configmap.yml.sample no longer exists).

However installation still depends on it: Keycloak install.sh will fail if the configmap has not been installed.

Also in various files dead links to it exist.