docs: fix broken internal markdown links

[Goutham-AR]

Fix broken internal markdown links in documentation files:

• Replace references to non-existent runs.md with customruns.md in pipelines.md
• Fix malformed anchor link in podtemplates.md (#./workspaces.md -> workspaces.md)

Fixes #9498

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[linux-foundation-easycla]

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• ✅ login: Goutham-AR / name: ArGouthu (7c445ae)

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[Goutham-AR]

/kind documentation