Add comprehensive documentation with corrected FQL syntax to README.md (#23)

* Initial plan

* Add comprehensive documentation to README.md

Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

* Fix unsupported FQL syntax based on reviewer feedback

Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

* Remove unsupported comments and fix if-else and END syntax issues

Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

* Fix FQL syntax: remove ENUMERATE, use SET_KEY, and remove pagination example

Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

* Remove unnecessary LET assignment from SET_KEY usage

Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ziflex <1607148+ziflex@users.noreply.github.com>

Author: Copilot