Manifestos have been used by software and agile development teams for many years. One of the most famous ones that most agile teams have been exposed to is the agile manifesto.
The goal of these manifestos and other similar guidelines is to ensure software teams are on the same page and have a DNA in place that they can all rally around and work towards. As you can imagine and can observe for yourself with a quick Google search, the value of having a manifesto or guiding principles is a controversial topic.
While some existing manifestos are good starting points for any team, you should only look at them as such and create a set of core principles and values specific to your team using a collaborative process.
Below is an example of a good starting point for your own Development Team Manifesto.