put https://api.shift.io/v3/assets//metadata/
Changes the value in a specific key/value pair
To update the value in a key/value pair, you must provide the asset id and key as path parameters, and you must specify a new value as a body parameter. This allows you to change a value without affecting the asset’s other key/value pairs. For example, you might want to update a file’s “Location” metadata from “LA” to “Los Angeles.” This request allows you to change the value to “Los Angeles,” while keeping the rest of your existing metadata intact.
A 204 code is returned when the value is successfully changed.