docs: add config generation docs in feature (#304)

* - add config generator docs.

* - added examples to understand the mergeType better.

* - add links.

* - added recommended settings section.

* - improved description of input sources.

* - formatted code.

* - improve the question answers.

* - renamed file to config-generation.md

* - added remaining sections.

* - added FAQ section.

* - added graphQL config examples.

* - added to sidebar

* - lint formatting.

* - fixed merging example.
- fixed json examples

* - added backlinks.

* - formatting fixes.

* - add backlinks

* - fix formatting

* - format json and yml.

* - fix yaml.

* - typo fix spelling.

* - removed duplicate sections

* - made input to h4.

* - change proto to gRPC.

* - format json and yml sections.

* - fixed yml indentation

* - removed input sources.

* - update manual efforts required for schema