Add Nested Documentation for 2.7 Related Features

[forestmvey]

Description

Added documentation for architectural changes from PR-1490. The added features covers the nested function used in the SELECT clause of an SQL statement. Future work has placeholders in documentation and can be added to with proposals as development continues.

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Merging #262 (b8732df) into integ-nested-select-doc (4bbd12a) will not change coverage.
The diff coverage is n/a.

@@                    Coverage Diff                     @@
##             integ-nested-select-doc     #262   +/-   ##
==========================================================
  Coverage                      97.16%   97.16%           
  Complexity                      4120     4120           
==========================================================
  Files                            371      371           
  Lines                          10373    10373           
  Branches                         704      704           
==========================================================
  Hits                           10079    10079           
  Misses                           287      287           
  Partials                           7        7           

Flag	Coverage Δ
sql-engine	97.16% <ø> (ø)

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[GumpacG]

Looks great! Not sure if it's appropriate in these docs but maybe add a simple example of mapping, data, and expected result of a simple query for devs in the future who don't have knowledge of nested in OpenSearch. May be appropriate in the use case section.

[forestmvey]

Looks great! Not sure if it's appropriate in these docs but maybe add a simple example of mapping, data, and expected result of a simple query for devs in the future who don't have knowledge of nested in OpenSearch. May be appropriate in the use case section.

Good idea!

[Yury-Fridlyand]

1. List new docs in index.md
2. Add links to demo you did for nested

[forestmvey]

1. List new docs in index.md
2. Add links to demo you did for nested

Thanks, I have added the files I added to index.md. There is already my demo video embedded in sql-nested-function-select-clause.md

[acarbonetto]

Looks good. Please address comments.