add back redirects that were removed

Author: boegel

mkdocs.yml

@@ -113,12 +113,15 @@ plugins:
         pilot.md: repositories/pilot.md # https://www.eessi.io/docs/pilot is mentioned in the EESSI open access paper
         gpu.md: site_specific_config/gpu.md
         rocm.md: site_specific_config/rocm.md
+        # training/ was renamed to training-events/ + <year> subdirectory was removed for Happy Hour sessions
         training/index.md: training-events/index.md
         training/happy-hours-sessions.md: training-events/happy-hours-sessions.md
-        training-events/2025/happy-hours-sessions.md: training-events/happy-hours-sessions.md
-        training-events/2026/happy-hours-sessions.md: training-events/happy-hours-sessions.md
+        training/2025/happy-hours-sessions.md: training-events/happy-hours-sessions.md
         training/2025/hackathon-eurohpc-user-days.md: training-events/2025/hackathon-eurohpc-user-days.md
+        training/2026/happy-hours-sessions.md: training-events/happy-hours-sessions.md
         training/2025/webinar-series-2025Q2.md: training-events/2025/webinar-series-2025Q2.md
+        training-events/2025/happy-hours-sessions.md: training-events/happy-hours-sessions.md
+        training-events/2026/happy-hours-sessions.md: training-events/happy-hours-sessions.md
   # Enable our custom plugin for json-ld metadata
   - inject_ld_json
     # link to any Markdown heading