docs: move the 0.32 upgrade guide to docs/upgrade (#2753)

Co-authored-by: Claude <noreply@anthropic.com>
Signed-off-by: Claude <noreply@anthropic.com>

.github/workflows/mixin.yml

@@ -9,7 +9,7 @@ on:
       - dashboard/*.json
       - docs/collector.*.md
       - docs/runbooks/**
-      - docs/example-*.yml
+      - docs/upgrade/**
       - docs/README.md
       - README.md
       - internal/metriccontract/**
@@ -24,7 +24,7 @@ on:
       - dashboard/*.json
       - docs/collector.*.md
       - docs/runbooks/**
-      - docs/example-*.yml
+      - docs/upgrade/**
       - docs/README.md
       - README.md
       - internal/metriccontract/**