What's Changed

Documentation 📔

• docs: remove presign from insert/replace example make it simple by @BohuTANG in #13376
• docs: user cases is not the Databend goal now so we removed them by @BohuTANG in #13378
• docs: add index page for all functions, thanks GPT4 he created for me by @BohuTANG in #13379
• docs: add index.md and better the markdown file name by @BohuTANG in #13380

Full Changelog: https://github.com/datafuselabs/databend/compare/v1.2.171-nightly...v1.2.173-nightly