docs: DEV-3288: Add doc how to load data from LS from ML backend (#2909)

* docs: DEV-3288: Add doc how to load data from LS from ML backend

* Update export.md

* Update export.md

* Update export.md

* Update export.md

* docs: Review and edit content

[fb-DEV-3288]

* docs: Review and edit content structure

[fb-DEV-3288]

* Update export.md

Co-authored-by: Anitha Muthu <anitha@heartex.com>
Co-authored-by: Max Tkachenko <makseq@gmail.com>