conventions - Example files naming

Fix inconsistencies in the naming of files in the examples/ dirs: some have the prod-type_blah-blah.adoc format, whereas others use type_prod-blah-blah.adoc.

Let's standardize on the latter because we want to keep the standard of having the type_ prefix in the beginning.

Example:

che-ref_a-kubernetes-secret-as-a-file.adoc -> ref_che-a-kubernetes-secret-as-a-file.adoc

1. Use git mv to rename all offending files.
2. Update all include:: statements to use the new file names.