## What changes were proposed in this pull request?
Fix some broken links in the new document. I have clicked through all the links. Hopefully i haven't missed any :-)
## How was this patch tested?
Built using jekyll and verified the links.
Closes#22772 from dilipbiswal/doc_check.
Authored-by: Dilip Biswal <dbiswal@us.ibm.com>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
## What changes were proposed in this pull request?
1. Split the main page of sql-programming-guide into 7 parts:
- Getting Started
- Data Sources
- Performance Turing
- Distributed SQL Engine
- PySpark Usage Guide for Pandas with Apache Arrow
- Migration Guide
- Reference
2. Add left menu for sql-programming-guide, keep first level index for each part in the menu.
## How was this patch tested?
Local test with jekyll build/serve.
Closes#22746 from xuanyuanking/SPARK-24499.
Authored-by: Yuanjian Li <xyliyuanjian@gmail.com>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
