does anyone use salt in their pond for fish health

Many people do. I add pond salt mostly just in the spring because that's when fish are most vulnerable. I don't use the higher doses recommended on the container so as not to harm the plants and smaller animals.

Would table salt(use for cooking) work??

NO!!!! absolutly not. It has to be sea salt or pickling salt. And get a salt test kit to make sure you don't overdose.

Table salt is sodium chloride. If it's just sodium chloride, that is fine. If it contains iodine as well, in small amounts, it's fine (in fact recommended for tanks with freshwater shrimp) but a lot of iodine can cause thyroid problems which is why they say do not use table salt. Also, some table salt has anti-clumping chemicals in it. You just have to read the label.

Since other salts are just as inexpensive, there's no reason to use table salt. You can use aquarium salt, pond salt, marine salt (for making saltwater tanks artificially or from actual dried up sea water), or even plain (must be plain) sodium chloride sold in bulk at Home Depot for whatever use. If you use only small amounts of salt, there's no need for a test kit. If you want more than 0.05% sodium chloride, then yes, get the test kit. More than that amount and plants will start to wilt and microorganisms may die. Koi experts say to use 0.1% salt but that's the most you'd ever use in a pond. I probably use 1/10 that but only in the spring. A 0.1% solution is about 0.75 pounds of pond salt per 100 gallons.