DOCS: Improve Documentation on Write Support

[sungwy]

Feature Request / Improvement

We currently have Write support through two modes:

1. through the Table API
2. through the Transaction API

We also have support for different modes of writes like:

1. append
2. overwrite
3. delete

Which make use of different arg parameters.

It would be great to update our docs to describe each of these operations and API modes explicitly in detail as separate subsections, and pad in any missing details (like the use of overwrite_filter in overwrite)

[guitcastro]

@sungwy When using overwrite how can we compare fields between source and target? like:

  source.id = target.id and source.updated < target.updated

[kevinjqliu]

someone asked about merge/upserts use cases in the slack channel as well, similar to overwrite_filter

[kevinjqliu]

Examples of overwrite_filter

• Merge into / Upsert #402 (comment)
• Overwrite with filter division by zero error #1020 (comment)

[iamvyshnavi]

Hi, I am new to open source and would love to contribute to this issue. Can I work on this?

[shrutisachan08]

Hii, I would like to work on this. I can update documentation by adding separate subsections for each write mode(append, overwrite, delete). I can insert some examples like including about overwrite_filter usage. Please let me know if there are any formatting details you would like me to include. Please assign me this issue.