docs: update broken links

[dongsam]

Description

Bullet Points

• fix broken links
• update demo doc/link for Add demo documentation to demonstrate how to use budget and farming modules farming#121

References

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• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
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• Wrote unit and integration
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
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