[docs] Migrate docs from AsciiDoc to Markdown (#8496)

    Deletes all static .asciidoc files of the previous documentation system (this files can still be updated on the 2.x / 1.x branches).
    Places new markdown content for reference, release notes, known issues, deprecations and breaking changes sections. This content will eventually be replaced by automatic generated content.

---------

Co-authored-by: Colleen McGinnis <[email protected]>
Co-authored-by: Peter Brachwitz <[email protected]>

Author: 3 people

Makefile

@@ -497,11 +497,11 @@ check-local-changes:
 		|| ( echo -e "\nError: dirty local changes"; git status --porcelain; git --no-pager diff; exit 1 )
 
 # Check if the predicate names in upgrade_predicates.go, are equal to the predicate names
-# defined in the user documentation in orchestration.asciidoc.
+# defined in the user documentation in upgrade-predicates.md.
 check-predicates: CODE = pkg/controller/elasticsearch/driver/upgrade_predicates.go
-check-predicates: DOC = docs/orchestrating-elastic-stack-applications/elasticsearch/orchestration.asciidoc
+check-predicates: DOC = docs/reference/upgrade-predicates.md
 check-predicates: PREDICATE_PATTERN = [a-z]*_[A-Za-z_]*
 check-predicates:
 	@ diff \
 		<(grep "name:" "$(CODE)" | grep -o "$(PREDICATE_PATTERN)" ) \
-		<(grep '\*\* [a-z]' "$(DOC)" | grep -o "$(PREDICATE_PATTERN)" )
+		<(grep '^    \* [a-z]' "$(DOC)" | grep -o "$(PREDICATE_PATTERN)" )