Docs: Add SQL query example

[ektravel]

Add a SQL query example showing how to pass dynamic parameters.

Tested using CURL:

curl "http://localhost:8888/druid/v2/sql" \
--header 'Content-Type: application/json' \
--data '{
    "query": "SELECT \"arrayDouble\" FROM \"array_example\" WHERE ARRAY_CONTAINS(\"arrayDouble\", ?)",
    "parameters": [{"type": "ARRAY", "value": [999, null, 5.5]}] 
}'

Returns:

[{"arrayDouble":"[999.0,null,5.5]"}]

This PR has:

• been self-reviewed.

[vtlim]

Need to also update the query to use the string variable