docs: concepts and building_applications migration (#3534)

# What does this PR do?

- Migrates the remaining documentation sections to the new documentation format

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## Test Plan

- Partial migration

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docs/docs/distributions/k8s/hf-token-secret.yaml.template

@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: hf-token-secret
+type: Opaque
+data:
+  token: ${HF_TOKEN_BASE64}