Some people might call this a want ad (ad here is short for advertisement).
Want ad is a generic term used for the place where people post goods for sale or advertise for services wanted. Some newspapers have a want ad section. Some want ads have one particular focus, like automobiles for sale, or apartments for rent.
In the case of a local supermarket advertising local jobs, some might think want ad is too much of a stretch, and that want ads should be broader in scope than one local store. But published definitions allow for some wiggle room. M-W defines want ad as:
a notice in a newspaper, magazine, etc., that lets people know about something that you want to buy or sell, a job that is available, etc.
While TFD says:
a classified advertisement in a newspaper, magazine, etc, for something wanted, such as property or employment
Sometimes these are also referred to as classified ads. Personally, I would regard classified ads as something more widespread than a local store (I picture something like this newspaper page, e.g.), but I think want ad might work.