docs(sre): mirror related/tags/tier attributes into the German anchor

The German Site Reliability Engineering anchor carried only categories,
roles and proponents, while the English file also has :related:, :tags:
and :tier:. Mirror those three (and the blank line before the collapsible
block) so the EN/DE attribute headers match the rest of the catalog.
Functionally a no-op — metadata is derived from the English file — purely
source consistency. Follow-up to #561.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: raifdmueller

docs/anchors/site-reliability-engineering.de.adoc

@@ -1,7 +1,11 @@
 = Site Reliability Engineering
 :categories: development-workflow
 :roles: devops-engineer, software-architect, team-lead, software-developer
+:related: five-whys, spc, control-chart-shewhart
 :proponents: Ben Treynor Sloss, Betsy Beyer, Chris Jones, Jennifer Petoff, Niall Richard Murphy
+:tags: sre, reliability, slo, error-budget, observability, devops, incident-response, toil
+:tier: 3
+
 [%collapsible]
 ====
 Vollständiger Name:: Site Reliability Engineering (SRE)