cspell: allow argjson, a jq option used in dev/sync-review-comments.sh

Co-authored-by: Amp <amp@ampcode.com>
Amp-Thread-ID: https://ampcode.com/threads/T-01a08fee-74b4-76dc-aaf9-d1245d68fdc9

Author: marcleblanc2

cspell-allow-list.txt

@@ -40,6 +40,7 @@ appendonly
 appengine
 appgw
 ARGF
+argjson # jq option
 atoburl
 atoi
 attnum