jq: Add example for constructing new JSON object (#4172)

Co-authored-by: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>

pages/common/jq.md

@@ -27,6 +27,10 @@
 
 `cat {{file.json}} | jq 'map(.{{key_name}})'`
 
+- Output the value of multiple keys as a new JSON object (assuming the input JSON has the keys `key_name` and `other_key_name`):
+
+`cat {{file.json}} | jq '{{{my_new_key}}: .{{key_name}}, {{my_other_key}}: {{other_key_name}}}'`
+
 - Combine multiple filters:
 
 `cat {{file.json}} | jq 'unique | sort | reverse'`