[Confusing example in documentation](https://github.com/documaster/documaster-api/blob/c35e3454fab85e6ce9d63a0a3e7073b62f3a3ffb/v1/examples.md?plain=1#L546-L569). With both the object *id* in the url and *post* data, the server returns **400**. Fix the example and clarify the [update endpoint limitations](https://github.com/documaster/documaster-api/blob/c35e3454fab85e6ce9d63a0a3e7073b62f3a3ffb/v1/endpoints.md?plain=1#L558).