Add jagdish-15 as contributor for Complex-Number exercise (#2854)

This is for his work in commit f37d6a8.

---------

Co-authored-by: Kah Goh <[email protected]>

Author: jagdish-15

exercises/practice/complex-numbers/.meta/config.json

@@ -6,6 +6,7 @@
     "aadityakulkarni",
     "FridaTveit",
     "jackattack24",
+    "jagdish-15",
     "jmrunkle",
     "kytrinyx",
     "lemoncurry",